It seems winning huge is def. possible.

http://www.coinflip.com/news/ziigmunds-sick-online-blackjack-winnings.html

On his latest blog entry for Coinflip, Ilari "Ziigmund" Sahamies talks about his "extracurricular activities", namely his raids to the blackjack tables on Betfair. After two short sessions Ilari is up more than 500k and the good folks over on Betfair must be tearing their hair in desperation.