Today's daf indicates that gambling is an asmachta and asmachta is not koneh. I don't quite understand this. Someone who gambles, whether it's at the race track or card table knows that the odds are not necessarily in his favor. There's a chance he'll lose and he's aware of that. If he's at a casino the odds always favor the house. Yet the Gemara seems to think that he doesn't expect to lose so he really doesn't mean it when he enters into a bet. Would the situation or the psychology be different in Chazal's day then today?
B'kavod, Sam Kosofsky
Actually, it is a Machlokes Rishonim whether Mesachek b'Kubia - gambling - is an Asmachta or not: the Rambam (Hilchos Gezeilah 6:10) holds that it is and Tosafos (Sanhedrin 24b) holds that it is not. This Machlokes is propagated forward by the Mechaber Shulchan Aruch and the REM"A. So according to the Ashkenazim, gambling is not considered an Asmachta and the money rightfully belongs to the winner. The reason, Tosafos explains, is that the gambler knows that it is not completely in his power to win every time and therefore he puts his money down with the full intention of parting with it if he loses. This is true even for gambling where skill is involved (such as Kubia) and certainly for gambling that depends completely on chance such as the roulette table.
According to the Rambam it probably doesn't matter what kind of gambling it is; it is always considered to be an Asmachta(see Shulchan Aruch, CM 207:13). It's not that he is unaware of the possibility of losing, it's just that he feels confident that despite that possibility, he is going to win - otherwise, why is he betting?.
Chag Sameach,
Yonasan Sigler
This is not a Psak Halachah