I don’t know. I just think that the misery that life doles out to people is so varying that making any kind of general statement is a waste of time.
Any old asshole, as you say, who’s putting in no effort but is living swell, that guy is irrelevant to the question of “life’s misery,” and whether “things get better.” Random shit happens, whatever, but these hypothetical random asshole doesn’t have to worry about things getting better in the first place. The fact of the matter is if you’re stuck in the dumps, you can wait for “life” to miraculously give you a hand (highly unlikely), or you can get off your ass and try to help yourself. The alternative, doing nothing and complaining about your miserable life until the end of time, is only going to make things worse for you.
Shooting down every possible statement with nihilism isn’t exactly emotionally supportive. I don’t think persistent pessimism is really going to get you anywhere.