In any case, you are wrong about one thing. 90% of the people on here do run sign businesses, so know how to do their own design work. None of them have been wowed and begged you to buy the site have they?
This is the mistake you made. You thought the website would appeal to proper signmakers, but why would they need bad AI designs when they can do decent designs themselves, and also exactly what their clients want, rather than some generic cartoon image?
Your site at best would appeal to people at the unskilled end of the business who just want to sell cheap decals of generic designs to people for a couple of dollars and print them out at home. Sadly for you, none of these people have hundreds of thousands to spend on a website