So each and every one of those companies made mistakes, and most of them died. My little band of friends and me probably held on the longest but we also made plenty of mistakes but at least ours weren't of the fatal variety.
Even so, knowing it was a great idea and having all that knowledge and experience gained over those years I still would not know how we could have avoided the cap on our growth and how we could have staved off the inevitable.
Eventually lots of people made a ton of money of that same idea, with execution that rivaled or beat ours handily, or with a shift of focus to a different niche (there were 100's of those niches and some of those are super profitable).
If my team and me would have been better at the execution part, if we had been more business savvy we might have been able to lock up the market.
Great ideas I have every day, you can have them, I suspect that your ability to execute on average is about as good as mine or worse so I'm not too worried about competition in the earliest phase of an idea hitting the market. But once a market has been validated the parties that enter that appreciate the idea and that are good in execution, they'll go places.
Because you won't be able to keep your idea secret and hit the market at the same time, best case you'll be able to keep your idea secret until you hit the market, but when you do you had better be ready to lock up that market in a very short time otherwise you will just be another 'also ran'.
My story is one of a reasonably good team, reasonably good execution and a bunch of timing and other mishaps and a general problem of being 'green'. There was absolutely nothing wrong with the idea.
Good ideas have value: to the right team. Even bad ideas properly executed have value to the right team.
But good teams and excellent execution are far more rare than good ideas.