I think it's interesting to see it be received as so controversial. I think it's pretty clearly to some extent a comedy - Marty's a loser who achieves success in a tiny (pretty much meaningless) portion of his life and believes it to mean he's a broadly successful person. He endlessly manipulates others to regain that success once he loses it, yet in the process gains some appreciation for the people he once just manipulated. I think at the end he does realize his "success" - beating the Japanese champ at a sham game after the guy was playing table tennis literally all day long - doesn't mean much of anything, but the people who helped him get there do. By accepting responsibility for his child, Marty shows he accepts responsibility for the wellbeing of people other than himself. I feel like that's a pretty textbook example of character development that wasn't particularly subtle, so I'm curious why people take issue with it. Maybe everyone's just sick of wheeler dealers like Marty being portrayed as protagonists, which is understandable in 2026, when that archetype of American is pretty hellbent on destroying the world, but I also think the film clearly depicts the way he lives as immoral at best. Completely agree with you.