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.
You're going to need a hard discipline to follow that $2 allocation for your gambling. For someone who only have this much of an income, I think he'd best look for another job, make it 2 or 3 jobs to meet ends.
But seriously. If a person is into Bitcoin, I doubt he is only earning such a small amount to because if he had thoughts on investing chances is that the person has more to spend.