I'm sure Drake has other businesses that can provide him with income aside from what he does, which allowed him to earn such a fortune. With such a large stake and having a gambling problem, it won't be easy to deal with it but Drake has made it this far and chances are, he'll be betting on something else again.
Hopefully, his children can help his father overcome his gambling addiction because, after all, gambling addiction problems can become big if not accompanied by strong self-control.
He has several lines of business (clothes line, record label, etc.) and he can certainly afford to make unnecessary expenses. But what makes you think that he has a gambling addiction? The fact that he made several bets does not mean anything. Perhaps this is just an advertising campaign or an action to stay in the information field (for him this is the most important business).
I think the gambling that drake did is a business for him. Rich people always think of how to increase their wealth so to be relevant always. No rich person that will depend just on a single job. Drake doesn't depend on rapping alone, he does other businesses like clothing and others. His betting isn't just luck it was a business calculation and that was why he involved lots of money into it.