I Refuse To Choose Between Ambition And Presence

Build with Attitude #3: How to product-think when AI builds at lightning speed

Casey Hemingway was ready.

The tool he built was ready. The market need was validated. The GTM playbook thought through. Clear-eyed unit economics. He'd done the work.

Then he shelved his product.

I don’t see it as a failure. I see it as a clean decision under constraints. Quitting can be strategic.

And I agree.

Welcome to the Build with Attitude Project

Why Authentic AI Development Stories Matter

I’m Karo 👋, AI product manager, builder of StackShelf.app, Attitudevault.dev and someone who believes that building value matters more than building what merely sells.

2025 feeds were flooded with “I vibe coded an app in two hours and already made $100K” posts:

These claims aren’t just unhelpful and misleading; they’re actively harmful by teaching extraction over value creation.

They reward performative certainty leaving no room for doubt, pivots, or the hardest call of all: walking away.

So I started collecting different stories. Not stories about tools, but about how people make judgment calls when certainty isn’t available.

Every second week, a builder walks you through how they actually think. Where they got stuck. What they changed. Why.

We’re all fans of vibe coding here. But we also believe in product thinking, craft, and building things that matter.

If you’re new to the series, welcome! Start here:
Build with Attitude - The Announcement
I Refuse To Ship Without Understanding Why It Makes Sense with Jenny Ouyang
I Refuse To Amplify Hype That Ignores Who Pays The Price with Dee McCrorey

The Product

Queenstown, New Zealand is an adventure town.

The kind of place where everyone owns a kayak, a set of skis, climbing gear, maybe a mountain bike or two.

Most of it gets used twice a year.
The rest of the time it sits in garages, while a tourist down the street pays premium prices at a rental shop.

Casey noticed this. And he saw something else: that Queenstown is a tight community town, where people know each other and do the same activities.
And where renting gear is already normal, it’s just strangely formalized and expensive.

So he built GearShare.
A peer-to-peer rental marketplace for outdoor gear.
Rent from your neighbour instead of a shop. Booking, payments, messaging, trust and safety - the necessary parts, all included.

He wasn’t inventing something new. Just shifting who you rent from.

It was a serious attempt at solving a real problem: expensive outdoor gear sitting idle in garages while others nearby either buy duplicates, miss out, or pay premium rental shop prices.

The Builder

Casey’s origin story isn’t about gear rentals.
It starts earlier. And, unfortunately, darker.

I lost my ultra-running identity to chronic fatigue syndrome before I turned 30.
I spent years learning that who you are can’t depend on what you can do.

My heart breaks for him, honestly.
I can only imagine the toll. My stepfather is an ultra-runner and Ironman. If he couldn’t train, he’d be devastated. For people like that, movement isn’t a hobby. It’s structure. It’s meaning. It’s how the day makes sense.

When you’ve already had your identity stripped once by circumstances beyond your control, you develop a different relationship with ambition.
You stop confusing motion with progress.
You get very clear, very fast, about what actually matters.

I refuse to choose between ambition and presence, Casey says.

You see, while Casey was building Gearshare, life was doing what it does best: escalating.

I started this in 2023, when my wife was pregnant with our first daughter.
We made a very adult agreement: I could pursue it if I proved it was viable while keeping my day job. Only then, after a seed round, could I switch.

Then came August 6, 2025.
The day before our daughter’s first birthday.

We found out we were having twins.
Due March 10, 2026.

At that point, the decision didn’t feel dramatic, it felt mathematical. I can’t do this with these constraints.

By then, he’d been building for a little over two years. Long enough to understand what the work actually required:

• Marketplaces demand sustained, hands-on activation

• You can’t pause a cold-start and resume it when life calms down

• The network either exists or it doesn’t

So Casey chose presence.

And called it what it was: a life strategy, not surrender.
Sometimes the most ambitious decision is knowing when not to push.

The Stack

Stack choices are rarely about tools.
They’re about decisions: where to allow speed, where to demand rigor, and where to refuse to compromise.

In Casey’s case, the boundaries are explicit.

• Lovable for quick greenfield experiments

  • Priority: momentum over perfection

  • Casey optimizes early exploration for speed and low cognitive load. In greenfield work, the goal isn’t correctness or elegance, it’s learning.

  • He’s choosing a tool that lets him test ideas before they calcify, fully accepting that some experiments are meant to be thrown away.

• Claude Code for anything production-grade

  • Priority: judgment, safety, and long-term reliability.

  • This choice reveals a hard boundary: production work deserves constraints, clarity, and explainability.

• Cursor with Opus 4.5 for debugging and incisive changes

  • Priority: precision.

  • Debugging is where weak thinking gets exposed. By pairing Cursor with Opus 4.5, Casey is optimizing for targeted reasoning

• ShareTribe did the boring, necessary work: bookings, payments, messaging. Trust and safety. Which meant Casey didn’t have to.

  By letting the foundation handle the table stakes, he could spend his time on the parts that actually make or break a marketplace: referral loops and category-specific onboarding.

What this tells us about Casey as a builder:

• He moves fast where the cost of being wrong is low

• He slows down deliberately where trust is at stake

• He uses AI to sharpen thinking, not replace it

Biggest Learnings

How little of a marketplace is ‘the product’ and how much is forcing a network into existence.

This is the thing most vibe coding tutorials on Youtube skip entirely.
They show you the UI.
They walk through the tech stack.
They screenshot Stripe payments.

What they don’t tell you is that:
- a marketplace MVP is maybe 10% of the work.
- the other 90% is activation: convincing real humans to show up and list things.

As someone building Stackshelf.app (a Substack marketplace), I relate to this deeply.

Another hard lesson was this:

How easy it is to confuse building with preparing to build.

I set up production-grade analytics before anyone had even seen the staging URL.
Not because I was avoiding validation, but because I needed everything perfect before showing it.

I’ve seen this same pattern show up again and again across different builders.

• people implementing edge cases before the happy path works

• setting up team roles when the team is you

• adding approval workflows where no approvals are needed

• adding permissions, roles, and access control to a one-person app

These paths are often recommended by the AI. And it takes judgment to know when to ignore them.

Casey didn’t learn that judgment from tutorials.
He learned it the only way it tends to stick: by building.

Attitude here is knowing when advice is technically correct and deliberately ignoring it until it actually matters.

Where AI Helped (And Where It Lied)

Casey’s AI critique is one of the sharpest I’ve seen in this series:

Generating convincing ‘best practice’ lists that smuggled in hidden complexity, especially around trust and risk.

Boom.
This is the AI trap we should probably talk about more:
- the AI suggestions seem reasonable
- the output looks professional
- everything feels reassuring

But buried inside those neat bullet points is implementation complexity that only reveals itself after you’ve committed. After you’ve wired it. After you’ve announced it. After users now depend on it.

What he rejected from AI:
Anything that would create fake traction or explode scope when the only goal was proving real local liquidity.

I just love this!

How many vibe coded marketplaces have we all seen that exist for a day or two and proudly claim 300,000 users?

Casey chose transparency instead. And I respect that.

I made a similar choice with Stackshelf. I show exactly how many store referrals we’ve made. It’s not a flashy number. As of today, it’s only 5,039. But it’s real. And it’s growing.

When I asked Casey what would have been different without AI, he said:
Slower iteration on docs and strategy, but the core constraint (my time and presence) wouldn’t have changed.

AI accelerated the parts that didn’t matter. The constraint was never speed. It was founder presence.

Casey’s Advice

Don’t use speed as a substitute for truth. Ship the smallest thing that forces real user behaviour.

Three things worth underlining:

• Speed is not the goal: Shipping fast doesn’t mean you’ve proven anything. Speed without feedback just gets you to the wrong answer sooner.

• Real behavior is the test: Not signups. Actual humans doing the thing you built because it solves a problem for them.

• Truth over traction: You can manufacture metrics. You can’t manufacture product-market fit.

The uncomfortable part is that truth often grows slower (and looks worse) before it gets better.

What We’re Learning

There are many ways to build a marketplace.

You can push halfway. Keep it alive just enough. Chase activity without reaching liquidity. Burn evenings and weekends manufacturing momentum that resets the moment you stop.

A lot of marketplaces die that way; not in a dramatic failure, but in slow exhaustion.

Or you can build with attitude:

• acknowledging that marketplaces are activated, not launched

• understanding that cold starts don’t wait for life to calm down

• choosing sustainability over heroic narratives

• understanding that constraints clarify what matters

• respecting your own time and energy

Casey could have kept going. Kept the story warm. Kept proving just enough to justify another month.

Instead, he made a clean decision under real constraints, protecting his time, his presence, and his family.

Responsibility doesn’t shrink your ambition, Casey says. It sharpens it.

And I agree.

Final Thoughts

I started this project thinking I should explain what building with attitude means.

Then I read the submissions.

Now I think it’s better if the meaning emerges from the builders themselves. We’ll define it together. One builder at a time.

Read my full interview with Dee.

Read my full interview with Jenny Ouyang

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Additional Resources

👉 Vibecoding Resource Hub

👉 Vibecoding Guide From 2 Builders Who’ve Shipped

👉 UI Prompt Pack

👉 Rules-For-AI - Guiding Prompt

What’s Being Built in the PwA Community Right Now

• Patricia Juarez @ AWS built WonderLead RePLAN: year-end review & strategic 2026 planning worksheet

• Andreea Dalia Lazar, PhD built a guide on how to integrate rigour and critical thinking when using feature prioritisation frameworks

• Justin built a Free Illustrations Library: Human-made illustrations only!

• Finn Tropy built StackContacts: the only CRM tool I use for managing my Substack subscribers.

• Jenny Ouyang built a custom Deal Hunter

• Bobby is launching the alpha for Projekt, a prompt engineering tool built from the ground up for designers, design engineers and builders. Waitlist is open!

• Dean Peters built a Github repo with skills for product managers

• Calder Quinn built HALO (High‑fidelity Alignment & Logic Overlay), a framework for building a stable AI companions.

  

Build It. I’ll Help It Get Seen.

You don’t need to do everything alone.
As a PwA member, you can list your projects on StackShelf App: an online directory I built so your work is discovered by readers, fellow builders, and AI. As of today, StackShelf has redirected 5,039 unique visitors to creators’ product sites.

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