as I recall, vodka is an unusually pure spirit; you can drink a lot and not get a hangover (though you will still get drunk, of course). Alcoholics will get alcohol from anywhere they can, and if he has access to vodka that will be good enough for him, as it has been for generations of Russians.
But any change does have to come from within himself, I'm afraid. It's an illness, and he has to acknowledge that he has a problem, and wants to solve it. Money won't help. Yes, you should stop worrying, and no, of course you can't; I'd be exactly the same in your place.