You can be pretty sure that it is. You should definitely do competitor research, but also don't reject ideas just because someone's already doing something similar. Execution is much more important, and the details do matter.
Totally agree with you. Ideas are cheap. I don't know the exact statistics but I found that most of the times, a person's startup idea will be already done by someone else. You need to do research for your idea nonetheless. But just don't get dishearten so quickly when you see that someone has already executed similar ideas.
Well most startup ideas aren't new. Someone somewhere will be trying to or already has done what you might be thinking of doing in one form or another. I think you should look it form this perspective, google intensely about it, check out all those who have done it and how you could do it better.that's what Drew Houston creator/founder of dropbox also did when he started out and that is what most startups do.
Google, search the app stores, check Twitter... those will get you an idea of who the big players in the market are. Also AngelList may have some competitors/similar startups