I can gamble even though I have a fairly small income like $100 but maybe my bet amount will be very small, probably my largest deposit amount is no more than $2 and it certainly won't be felt especially if I use it in a type of slot game, but nothing is impossible to get a big win even though my bet is small if for example I manage to get very good luck, but it seems much better not to force the situation when my monthly income is small, I better use it for things that are more useful and beneficial.
It's really wise to consider other important needs first before you allocate a huge amount for gambling, if you allocate $2 that's just a -2% from your salary and such amount would not even be felt unless the remaining $98 would not be able to foot all your bills for that month but if it can feel your bills, you wouldn't feel trouble with the small amount you allocated for gambling and it's even possible that you can double the $2 to $6 and withdraw the $4 profit.
For me, I always recommend at least 2-5% of one’s income, reasons because that amount taken out from your income wouldn’t be felt that much if lost. Let’s be realistic, if someone is earning $100, except the person is an extravagant spender, they should have at least 10% as their discretionary income, and taking out at least half of that discretionary income wouldn’t really hurt cos you’re sure to have already sorted out your other expenses for that week/month, so even if you end up losing it, you wouldn’t feel much of the impact.