I consider making for a living is where you can always make money in long term, gambling can make money but it's just only for few times and it's impossible if you're only depends on gambling as your main source. Gambling isn't a long term money making because luck isn't always in your side and there's a chance you will get scammed from fraudulent casino. Not to mention your account might get frozen, restricted, or betting limit.
Gambling can't provide a passive income of can't be a stable source of living because of its risks. It can't provide a guarantee of winning all the time so we can't expect to gain a regular income from it. Most people earn through luck and by skills and strategies but it can't be a continuous source of funds. We can do it as a habbit or for entertainment purposes but it is still better to have a stable income aside from it.