We've been full time 100% YouTube income for over a year now, I quit my job October 2014 but could have quit a few months earlier than that. My advice for aspiring YouTubers who would like to become full-timers is to be original, find a market that's not flooded already, but something that could have wide appeal, then do it so well that you get a firm foothold before others start imitating you. Also, don't expect overnight success, it's not entitled to you, and have fun with what you're doing.
It's probably not a realistic career goal to become a full-time YouTuber, I mean it's possible but the odds seem very steep. Even very popular channels aren't always making full-time income from views alone--a million views a month probably won't even cut it for most lifestyles. So make sure you have other interests to keep you busy.
If you put complete focus on just becoming a full-timer you are bound for a long difficult and disappointing ride. But if you include YouTube as just part of your life, one of many hobbies and things that keep you happy and hopeful, then you're more likely to stick with it and not just be chasing the latest trends all the time. I made videos on and off for a good 7 years while working full time at a bank. It was never my life goal to become a full time YouTuber but I can't say this was a big accident either. Position yourself for success and stay persistent, and that increases the odds of something sticking or whatever it takes to bring in the big views.
Good luck and remember that every view is a person, not just a view! If you can convince 1 person at a time to watch, then you can get some momentum going.
but I know that some people on here make a living off of youtube and thats great for them 
hahaha
