What makes it even sadder is he's probably genuinely depressed, but by doing this to himself he's short circuiting his brain for a flood of endorphins. It works out in the short term, but it creates a dependency. Normal endorphin generation throughout the day isn't enough anymore. The minute he stops he's going to find himself in a depressive hole so deep nothing will get him out. Only the grace of God can save him, but he doesn't believe in any of that.