Gambling is easy money - gamblor get temporary profits sometime but they cannot depend on gambling to run their monthly income.
Its a matter of luck and that is it. If the day is unlucky you can loose all the money in a jiffy.
I'm really sure a real gambler will know how much are their losses every month, this mean they're already knowing gambling isn't a primary source nor side job. Moreover they didn't need to wait a month to know if gambling is isn't a money making, just try 7 days consecutive and you will know the result.
~snipped~
Gambling may be just an entertainment or a place where they gamblers try their luck using some of their money to hit the jackpot. Gamblers who already know that they will eventually lose will not force them to continue playing. it doesn't take 7 days to find out gambling can continue to produce, in just one day they will get an answer. If you have won, take it and don't place a bet again. The one who always wins and has a lot of advantages is only a bookie.