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.
Especially when you lose, you will lose more if you are ambitious to win in the next game. Gambling ambition is the biggest supporter of losing. No matter how much you win, you end up losing. So never trust gambling money.
Not really know what you mean about "never trust gambling money" because money is money, it's just a matter of the regulation where it can be considered as high illicit income.