Honestly, a business doesn't need to be based on a good idea or even unique idea. All you need to provide is a service or product that is competitive with others. It certainly helps if you're the first one to figure out a solution to some problem that other people have but there are as an example a bunch of sushi shops in most major cities.

All you need to do is provide good sushi, preferably better than most others, and people will buy it when they become aware of it. Since you're starting from scratch, it is a high likelihood that you will have some failing ideas or projects but in time you will learn what works and what don't.

Good luck and there is no idea to share your dreams with negative people that give unconstructive feedback unless they have something that they can provide.