The toughest part of this is finding a product that people are willing to pay for. The sunk cost fallacy kicks in, and everyone doubles down on pushing the product and iterating until they finally have no choice but to admit failure. I think YC does a great job of getting people to ask what is the absolute least amount of work I can do to validate an idea. Can you send texts instead of build an app? Can you do it all manually for the first 5 customers? Be quick to throw away things that aren't working, you don't have the bandwidth as a solo founder to make a perfect product, you NEED to see market acceptance to make it worth your time.