For fun of course. Otherwise you'd have seen me on TV already right? That being said, yeah, who wouldn't love to go on a month (or longer) roll/heater where you can't seem to lose and build up a roll large enough to play for real "pro" stakes? I just don't ever count on that being the case and am having enough fun risking $20-$40 in a day at this point.
I usually make a little bit each day and don't usually dip very much and still like playing the freerolls to see how i stack up on the leaderboard too! Being a USA player, it's been fun this last year building up a roll from nothing but freerolls to the point i'm at as well. I keep waiting for PS to get back into the USA game and let me play the $400+ i still have on there too. Optimistic i know...