Pops gives SA a hometown discount. No different than his players.
If Pops went on the open market, what do you think he'd really command? Easily $7-10M+.
And why do we care what coaches get paid? It's still a fraction of the salary of the best players on the team, and it doesn't influence the cap. Heck, it's often less than MLE money and that barely gets you a decent rotation player.
Let's also not forget that not all coaching gigs are the same. The size of the market impacts the money available, as well as the desirability of the gig. Part of why Spoelstra makes less is because if the job was vacant there would be a line going out through the door of quality Head Coaches that would want the job.
Supply and demand. High quality coaches can drive up the salary simply because there's not a lot of them. And high quality rosters can drive down the salary for the job since the best coaches prefer to go to teams that are ready versus jumping into a rebuilding gig.
Anyway, it doesn't affect a team's cap space and it comes out of the pockets of the billionaires, so why should I care?
J.R. Smith: "They were pretty much scoring at will. Especially my guy. I don't know what the hell I was doing on defense."
Raymond Felton : "The play was give the ball to Melo."