Someone once told me, and I very much agree with this statement, that if you ever really want to feel like a complete failure at photography just start browsing the photographs on 500px. Now, I have a 500px account and I do think that while I am very much an amateur photographer, I take some pretty solid photos. However, I still look at some of the images that get posted and think "I should probably just put my camera down and find another hobby" because, damn, these people are good.
I say that somewhat jokingly because I don't really get discouraged to the point of wanting to find another hobby but it leads me to an observation about the types of people that exist and how they react to challenge. There are those that see the images posted by these photographers and want to give up and then there are those that look at the images and think, "how can I take images on that level?".
That's the key to it all: persistence, especially when faced with photographic failure.