It's somewhat logical for him to act this way, but I'd look at it like this. He's almost definitely immature. He's of course hardly the only high draft pick in that boat.
What I really don't like is that he's obviously very selfish. Whether or not he feels he should have been "forced" to go to college, he had teammates. He had thousands of fans, most of whom he saw every day on campus. And you know what? He quit on them and half-assed it, because Ben Simmons doesn't need LSU, he's going to be rich and famous in the NBA soon enough.
He's still really good at basketball and really young. There are probably worse individuals in the draft. However, this is pretty lame on a personal level and may follow him into his next locker room. Hopefully he just has lousy advisors and he pulls it together.