When you are depending on someone for assistance because you want to gamble it means that you are risking what you can not afford to lose. Why because you don't have the money to gamble but someone have to give it to you before you can stake.
But when you have jobs that pays you money so well and you are gambling it means you are risking what you can afford to lose. Why because ones you lose your job will give you another money.
However, many people would say even if you have jobs but you are staking higher it also means you are gambling with what you can not afford to lose. Moreover it's true and I have to dauth but I have a feeling that ones someone that have a good paying job is staking more than what he can afford to lose, there is no different between addiction there.
I agree with you on the second paragraph of your definition of money you can't afford, once you have gone way above what you can't bear in mind to lose or likely feel fearful of losing such an amount of money, it doesn't matter whether you are working or not, whichever way you get the money dash or through job, take you for instance, that someone dash you money, let's say $20, you will be at peace losing $1 than losing $5-$10 out of it regardless.