“I build an MVP and then I show it to a few real estate agents that I found online or in personal network. People say that's awesome, I want to buy it now, and they actually paid for this. So that was the validation.”

Real validation is one customer who actually pays — not a survey

Validation is not a survey or a waitlist. Build a rough MVP, put it in front of the exact people you think will buy, and treat actual payment as the only signal that confirms the idea.