I worked for an online gambling company for several years in the analytics area. I saw young players rise meteorically, win millions (not exaggerating) and eventually go broke.
Almost everyone is human. Once losses start to mount, it's hard to play with according to the program and stay emotionally detached while your world is crumbling with every lost pot.
Never underestimate the cheaters. Most online poker players don't understand how rampant collusion is. Dumb colluders are easy to spot. Smart ones will stay undetected until someone gets greedy. Almost everyone is human. It's hard to maintain discipline.
I myself thought about playing online professionally. After I realistically evaluated my chances and my stats, it became clear that I would make more money on a guaranteed basis by being a consultant than a professional poker player. When you have a family that depends on you, stable income becomes very important.
Online gamblers live a very unfullfilling life: you are staring at several computer screens many hours each day, you don't really create anything and you have wild swings in your income. With exception of few lucky, hard working, disciplined and possibly intelligently colluding players you will not make good money in the long run.
In the short run, impossible is nothing. Play that tourney, enjoy a night in a casino. It's good fun if it's not your job.