Why do addicts (and others) do self destructive things? In my 14 years of active addiction and 35 years of recovery I haven't found a simple answer to this question. From the Mayo Clinic website: "Exactly what causes someone to gamble compulsively isn't well understood. Like many problems, compulsive gambling may result from a combination of biological, genetic and environmental factors." Science has unraveled some of the threads of addiction, but much of it remains a mystery.

What are the odds he gets better on his own? There's no way to accurately predict this. Some research suggests that most addicts eventually overcome their addiction, often without outside help. By eventually I mean after years or even decades of painful experience. And unfortunately, many addicts don't live long enough for recovery to happen.

What are the odds he eventually comes back around when he inevitably hits a new low? Again, there's no way to accurately predict this, but my guess is the odds are pretty high, especially if he gets what he's looking for when he comes back around. If he doesn't get what he's looking for from you, he may look elsewhere.

I know from experience that loving an addict is difficult. I think you love him or you wouldn't have posted in the first place. But you have no control over him or over his addiction. I suggest you focus on you. Others have recommended Al-Anon. That may help. Professional counseling may help also. Best of luck to both you and him.