I think there is a significant "uniqueness" to Hayward situation such that it really shouldn't be judged with in the same way other players are.
He signed with Boston after his age 26 season as an ascending first time All-Star looking to take his career to the next level. Instead, his next 3 seasons went:
1. Catastrophic potentially career ending injury game 1 of the season (age 27)
2. Struggled working his way back from that injury (age 28)
3. COVID pandemic and severe ankle sprain mid playoffs in the bubble (age 29)
During this time, his own team developed a 22 year old top 10 wing and a 24 year old top 25 wing. Hayward was heading towards being a top 15 player in the league, in the middle of his prime, and he had some of the worst injury/pandemic luck you can possibly imagine.
Now people think he should take less money for the second half of his prime and never really get the chance to establish himself as the player the thinks he is? All so he can be the jack-of-all-trades glue guy for the next Celtics championship team?
I doubt Charlotte was really his number 1 choice, but he didn't really have too many options in the end. I'm glad to see him playing well and think his decision was totally reasonable.
FWIW, in these super rich "the money is sort of irrelevant in the end" scenarios, I typically don't understand why athletes sign for top dollar to waste away on a terrible team. But Hayward's situation feels different to me. He only has a couple years left to see where he can get as a player.