I've produced a lot of garbage.
Not physical garbage (although I'm sure I've probably done that too), but digital garbage. Every line of code, every page on my wiki, every tweet I've sent out — most of it is crap.
But within all that crap, every once in a while I produce something great. Well, maybe not great, but better than most of what I've produced in the past.
Austin Kleon has dubbed this phenomenon Sturgeon's Law, named after science fiction writer Theodore Sturgeon, who once said that "90% of everything is crap".
Here's the challenge: how do you know what's good and what's bad beforehand?
You can't know. It's impossible.
"Uber for dogs" sounds like a dumb idea, until you realize that many doggy daycares offer to transport your dog for an additional fee. Twitter, when it first came out, probably also seemed foolish to lots of people with a restriction of 140 characters, but it's still one of the most heavily used social media platforms in the world.
You can't know how good something is until you make it. Create it. Put it out into the world. Tell others about it. You just might be on to something.