I always try to find at least one client who has a problem I want to solve and ask them to fund development of version 1. If no-one is ready to pay for developm

I always try to find at least one client who has a problem I want to solve and ask them to fund development of version 1. If no-one is ready to pay for development of version 1, it is a sign that I don't have a market and shouldn't waste time developing. So far, I have developed two profitable products using this strategy. Even if it doesn't work, at least you were paid for your efforts.