I don't either, when you factor in cost of living out in Cali... What they are supposedly offering him isn't really much of a raise.
This whole thing is just so odd.
It's all relative though. The cost of living might be double in the LA area (108% more, close to a double per this website:
https://www.bestplaces.net/cost-of-living/knoxville-tn/los-angeles-ca/3000000), but against a multi-million dollar contract that's noise if the coach has reasonable tastes in housing. If Barnes is currently living in a 500K house in the Knoxville area (just a WAG) he doesn't have to get as big a house in LA. His cost may double, even for a smaller house, but I don't think it's one to one. Cost of living has a fixed upper limit. I mean, food and gas and utilities, no matter how much they increase, will be a small proportion of a multi-million dollar contract. The only gotcha is the house, but Barnes and wife could always settle for a smaller house.