There's a whole lot of luck involved but
I think being successful is directly related to how much effort you put into it. If you sit at home in your basement playing to the tv, you'll still be there 10 years from now.
If you go out and push your music 18 hours a day and schmooze with the right people, and get on peoples asses constantly, you'll stand a far better chance.
It's kinda like buying a lottery ticket. The more tickets you buy, the better chance you get of winning.