Hell you could make some interesting T-shirts out of half of your art that I've seen just randomly browsing about. Live it up, the world is your oyster. You can be whatever the fuck you want, trust me.

Hey, don't even say that you're a failure. You are far far from that definition. Believe me, I know some people who are just a waste of time, an emotional strain and are truly a waste of space. You are not that. And there are no "ifs" because nobody will be any better off if you died. As a matter of fact, life would prolly be an even bigger hell than it is now if you died.
By the way, I won't tell you that you have potential. I hate that fucking word down to the core. You already have the ability to benifit from what you draw, its just a matter of getting people to notice enough to wanna pull out their wallets and buy it. I've seen people buy the most worthless shit out there, so if they're willing enough to do that, they'll be beggin to get your work once you show it off to them in a good amount.
As for becoming famous and all, I can't tell you much about that because I've given up on trying to predict the future. Sounds stupid that I even tried, but y'know things were once very nice and satisfying in my life and I was thinking everything would stay blissful. But of course it didn't stay that way and things aren't so nice in my life right now. I thought I would've been a great famous artist in the future too, but nowadays I hardly have time to draw and its hard for me to draw a lot of things. Turns out terrible when I attempt to do something different. Its hard to say where anyone our ages will end up in the future.
But you are definitely not going to end up being nothing because you aren't nothing. Don't just give up and die, because there are people that do care very much about you and would be devastated if you died.