I really don't like gambling what I can't afford to loose. Sometimes when one Gamble's big money and looses, the person tends to increase his stake and the cycle continues.
You should never gamble funds that you didn't plan to, because it will always get yourself into a situation where you lose funds you couldn't afford to.
As you just said, you can win/lose funds you earn in a month.
If you are betting funds that is equal to your monthly salary, I would stop gambling at all.
You should gamble for entertainment, if you bet your whole monthly salary and lose, you won't have money for living and it is very dangerous situation.
Always be responsible at gambling.