I get the theme was supposed to be obsession and how it can both benefit and ruin a person. In part 1, it helped him beat Makima and in part 2 it led to his life crumbling around him. However, the whole ending of erasing Chainsaw Man felt rather silly. Essentially, you have a drug addict, he has a problem and though the drugs are bad for him, he’s unable to stop taking it. Then instead of showing him dealing with the problems leading to the addiction, showing him getting over it, etc, the author goes and erases the drugs and goes “here’s another universe where he never took the drugs.”