Did he ask you to help him, or is that more your idea, that you think he could do better in life if he had someone to love and help him? Of course it's important to support our partner, our friends, our familiy members during challenging times, but I don't see that you love this guy "as is" - you don't enjoy him as he is in his everyday self. He needs to change a LOT of things before he will be okay in your book. But you call it "helping" him, assuming that anyone, everyone should WANT to fix these things - stop drinking, find a job - AND do it on your timetable, when you say "start".
You don't think he has the right to live the way he wants to live.

Maybe it's really your dad who didn't have the right to live that way, not after you were born. He should have been more responsible to you. But he wasn't. But you can't change the past by trying to relive it with this young man.

The is the reason you feel such love and tenderness for him over other, healthier men. I hooked up with unhappy people thinking I could help them too. It's kind of insulting to them, if you think about it. I wish you well.