Number of reasons he could go beyond money itself
1. Some driven people are wired differently - they are constantly looking for new challenges. Going somewhere else and winning a title there, trumps a chance to repeat again at the same place you have already been successful.
2. Maybe Hurley is primarily interested in on the floor coaching. While he is very successful at being an NCAA "coach" in the NIL environment, perhaps the extra elements that are now required for an NCAA coach just don't interest him. Perhaps he wants to focus more on the direct coaching aspect -- and while its many more games in the NBA, an NBA coach also just primarily coaches... all the other **** is handled by the GM's office.
3. It's the Lakers, Like the Celtics. They still have a certain legacy draw that other teams don't.