Here's a bit of a cheat code nobody really talks about. When you build the product AND you're the one out there pitching it, your feedback loop basically drops to zero. Someone throws an objection at you mid call? Congrats, that's a bug report with a human attached to it, delivered in real time, for free.
I lived this at my startup. I'd write code all morning and get on sales calls all afternoon, and the whiplash between the two turned out to be the best product education I ever got.
Demos are the real spec
You think you know what your product does. Then you demo it live to someone who could not care less about your architecture, and reality smacks you in the face. Every feature they skip right past? Dead weight. Every single thing they lean in for? That's your actual product. Everything else is just stuff you got emotionally attached to along the way.
The brutal part of founder led sales is also the best part: it's honest. There's no PM in the middle translating feedback into a ticket that loses all the context. It's just you, a prospect, and the truth. It stings sometimes, sure, but it makes you sharp real fast.
If you can't explain why someone should care in one breath, you don't have a product yet. You've got a demo.
So yeah, go sell the thing you built. Not because you love sales, not everyone does, but because absolutely nothing will teach you your own product faster than watching a stranger decide whether it's worth their money.