Another good point, sort of. Not saying I'm anywhere close to being a professional, but I've played against a few and have learned from their poker play.
If you have the chance to play against a really good poker player, I say do it.
Be watchful and learn every step they make. They may not be playing their best game because they're use to playing against pros, and in the back of their minds;
all other players are just wanna-be's, or the pro doesn't think a normal online player can do anything to hurt them.
It's all in the cards. Even a professional player has his/her bad day, week, and sometimes month.
Again, I'm no poker pro, but I've had plenty of days, weeks, and sometimes months where I could not get the cards to save my game.
The more you practice against the professional poker player, can make you better poker player.
Practice, practice and practice your game, because practice can make perfect.