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.
I do not think it goes that way and here is the reason why.
If someone says he can afford to lose, it means there is no effect on his financial status no matter how much he losses. It does not make him suffer a shortage of money to pay for his bills and daily needs. Even when the money he gambles is given by other people, as long as his gambling losses do not make him short of money he can say that he is gambling the money he can afford to lose.
While, gambling that can't afford to lose is a situation where when a person's losses make him unable to pay for his needs or the money he used is allocated to somewhere else, even if he has a job it does not exempt him that he is gambling with money that he can't afford to lose. In short, gambling can make a person short of money to support his needs, even with a high-paying job, it is labeled as gambling the money that a person can't afford to lose.