Doing this might actually save you from losing huge amounts and making terrible financial mistakes. As a gambler it's not advisable to stake more than 5 percent of what you earn monthly especially if you don't earn much. Gambling is a lifestyle and it's something you find yourself doing even when you don't want to, this is why you should set aside 5 percent of your income monthly and try not to exceed that amount whether you win or lose. A lot of gamblers seem to deviate from the plan when they are losing because they use all they have to chase their losses, you must learn to be disciplined no matter what
5% is actually make sense even you didn't earn much, if you earn much you might say 5% is too much.
Let's say you earn $300 per month, you only can gamble for $15.
But, if you earn $10K per month, 5% from $10K is $500, you might say it's too much to gamble for $500 because you ever get paid $300 per month.
When you're earn small, calculate in percentage looks make sense, but when you earn big, calculate in percentage doesn't make sense anymore.
There will be depends on how much his salary, so that will be the best if he know how much money he willing to spend in gambling. Using $15 every time he gambling will be okay if he can accept the risk of losing all of that money.
But if he allocates $30 for a month, no matter how many you playing gambling in that month, that will be good for him. He knows that he can not playing gambling for more than $30 in a month. So he will be careful when place his bet and always limit his gambling activity.
If you earn small, very small you don't have to playing gambling. That will make you in trouble because you must pay attention to your daily needs rather than playing gambling. You can playing gambling when you have more money so you don't disturb your daily needs expenses.