Okay. You can cross the street and have an accident and be handicapped for the rest of your life. You can't make sure of anything. You can estimate the probability of happenings. That's what makes you feel sure.

Do you have a family? If not, go pursue your dreams. I'm dropping Medical studies to do... well...freelancing on the side and coding stuff. No clear idea, but I like to start something (a small project/SaaS) and get busy with it.

I only can say one thing, I learned hopefully after not so long time (I'm 20): Stop doing Shit! Go and do something you like. Period.

By, when you get to the point where you have to choose with either your heart or your head (wallet, benchmarks etc.) picking the former.

Oh, and watch Steve Jobs at Stanford on this: https://www.youtube.com/watch?v=D1R-jKKp3NA