and the profit is not that great.and some times there is no public income according to the game rule. the master's income depends on luck. like some dice and blackjack games.
The income depends on odds I guess, it's something about statistics.
There is an odds the house can win from players, Take the coin tossing as a example, if you toss coin 10 times, you might get 8 outside and 2 insides, but if you toss thousand times, you will find the number of both sides will come close to 500, that's a function of odds. The same in the dice sites, the more players, the results will come closer the odds, and if the house has the odds advantage, then they will always win.
This is what I think, if there is something wrong, please correct me.