I feel like a weird industry has popped up that makes you feel like you can validate everything in advance. I think this comes from Product Managers in large, risk-averse companies that excessively try to minimize mistakes.

However, if you want to start a startup, you aren't optimizing for mistake minimization! You are figuring out if anyone cares as quickly as possible. You will only get true validation of this by seeing if people use your thing, and then iterating from there.

My advice would be - you have to _both_ talk to people and _at the same time_ create whatever your MVP is to launch as fast as possible. It might be a spreadsheet. It might be you doing stuff manually for them before building the software. Get something into their hands as quickly as possible.