Founders who nailed their ICP: what did you build, and who actually turned out to be the buyer? - I will not promote

I've read enough ICP frameworks to last a lifetime and they all say roughly the same thing: get specific, talk to users, narrow down. What none of them tell you is what that actually looked like in practice for a real company. So I'd rather hear it from people who've been through it. If you've got paying customers, I'm curious about: What did you build? Doesn't need to be a pitch, just enough context to make the rest make sense. Who did you think would buy it at the start? Be honest about the first guess. Who actually bought? Same people, or did it shift completely? What was the moment you knew? A pattern in sales calls, a churn cohort, one customer who used it in a way you didn't expect, what was the actual signal? How long and how many conversations did it take? I'd like a realistic sense of whether this is a 3-week thing or a 9-month thing. How narrow did you end up going? Everyone says "go narrower." Curious how narrow was too narrow, if you ever hit that. My current context : the thing I keep getting stuck on is that the people who are most enthusiastic in conversations aren't the ones who convert. I've started assuming the real signal is whether someone already has a janky workaround for the problem, spreadsheet, manual process, someone's intern, because that means they've already decided the problem is worth money.