Of course it's a huge contract, but he's the kind of veteran leader you want around your young, up and coming players. The more perplexing thing is $9M+ on their books for the next 3 years for a player who isn't even playing for them. It's not likely CHA was going to land any big FAs in the coming years, but that can certainly limit a team's options.
As for Hayward himself, I am sure the last 3 seasons were a whirlwind for him and he is probably just enjoying playing low-pressure, injury-free basketball as the 'best' player on his team. You don't go to CHA to compete for a Title. Some guys just chill out in their 30s in terms of their competitive nature; I know I did.