He'll still get his shot to play in the NBA, but probably the thoughts of grinding in the G-league and possibly never even making it up to the Show next year weighed on him. When the other option is to stay at the place you love, have a chance to win another natty, and maybe even more more money via NIL.
Hopefully he has a strong senior season and some team will give him a guaranteed contract next year, even if he's still a 2nd round pick. If you are 6'8 and can shoot 40% from 3, you'll at least get a chance to prove yourself.