1 million blue stars for this.
I watch a ton of basketball and I think KD gave 8 of the best years in NBA history to OKC, he doesn't owe them anything else. He was a free agent and made his own decision to go win championships and live in a nice area. He's also a fledgling investor and being in the bay area has hooked him up with tech startups/etc (probably just sucking his money but hey, if it's what he likes, he's more likely to find that in SF than OKC).
Check out this link with analysis on when KD chose to join the Warriors and honestly think about what you would do.
https://www.cbssports.com/nba/news/heres-a-plan-b-for-teams-that-strike-out-on-kevin-durant-in-nba-free-agency/OKC = Stay with Russ
SA = Superteam but not as superteam as the Warriors
Wizards = Probably not good enough to beat the Cavs
Lakers = He'd be alone and lose a lot
Heat = Alone and lose a lot
Houston = Read the article... it's pretty funny how they analyze them, but at the time they sucked
Celtics = Legitimate option, but at this point they were in the middle of a rebuild, we just didn't know they were ahead of schedule.
Then there is the warriors, go there and win a lot.
It's a pretty easy decision really.
As has been stated, I'm always surprised to hear criticism of a man making a career decision for himself and his family. He owes nothing to the league to give them a competitive product.