It's also easy to say you don't feel the need to make more than a barely livable wage when you're in high school. I also thought this, then my parents cut me off and made me work a job in college. Living paycheck to paycheck is awful.
But like another poster said you only train 2 hours a day so find something interesting that you like to do and go with it. I think the idea of being a full time professional runner is a bit ridiculous considering the pay. I know a guy that qualified for the Olympic Trials in the 800 while working full time at EY. It most definitely can be done