SANTA CLARA, CA - DECEMBER 28: Head coach Jim Harbaugh of the San Francisco 49ers watches the action against the Arizona Cardinals in the first half at Levi's Stadium on December 28, 2014 in Santa Clara, California. (Don Feria/Getty Images)

The writer is a contributor to The Post.

The University of Michigan’s decision this week to commit at least $40 million to Jim Harbaugh over the next seven years raised quite a few eyebrows. Forty million dollars — $5 million a year to start, along with a $2 million signing bonus — for a football coach?

Can jock-Armageddon, when the entire bloated-with-corporate-dollars sports world explodes, be far behind?

Actually, Armageddon has already pretty much come and gone in college athletics. The attitude of many players at the most visible schools was summed up by a tweet sent two years ago by Cardale Jones, who will start at quarterback for Ohio State in the national championship game on Jan. 12: “Why should we go to class if we came here to play FOOTBALL,” he tweeted shortly after arriving at Ohio State. “We ain’t come to play SCHOOL, classes are POINTLESS.”

To paraphrase “A Chorus Line”: Honesty 10, grammar 3.

Harbaugh won’t be the highest-paid coach in college football in 2015, even if you calculate his first-year salary at $7 million (bonus included). Alabama Coach Nick Saban will make $7.2 million. In fact, at least a dozen football coaches will make at least $4 million in the coming year. According to USA Today’s annual report on coaching compensation, almost every football coach among the 65 schools in the “power-five” conferences makes seven figures, and, as Harbaugh’s deal proves, there’s no sign of that trend reversing itself anytime soon.

To wring one’s hands and — correctly — point out the absurdity of a football or basketball coach making 10 times as much as the university president and more than perhaps 20 or 30 tenured professors combined is a waste of time. That ship sailed long ago. What’s more, if Harbaugh is successful, he will be worth every penny he’s paid — and more.

Remember when Penn State was fined $60 million by the NCAA in the summer of 2012 after Jerry Sandusky, the school’s longtime assistant football coach, was charged with sexually assaulting young boys? That sounded like a lot of money, even if it was to be paid over five years. Further study revealed that Penn State’s football team was netting close to $60 million annually.

Nowadays, with the bloated TV deals each of the five major conferences has made with the networks, along with the 12-year, multibillion-dollar deal with ESPN that funds the new college football playoff, having a successful football team is a little bit like having a bottomless ATM in your locker room. Not only is the revenue extraordinary, but the athletic departments — which are independent entities and, thus, not part of a university’s budget — are also tax-exempt. The charity that receives most of their profits? Themselves.

Big-time football schools are in a nonstop “arms race” to build Taj Mahal-like facilities for their athletes. They build bigger stadiums and pay coaches millions, and you can bet almost none of their coaches will soon be flying on a commercial jet to recruit.

Michigan’s football program has fallen badly in recent years. Since 2008, it has hired and fired two coaches and has a win-loss record of 46-42. Michigan Stadium, which once sold out all 109,000 of its seats for every game, had thousands of empty seats for several games during the just-completed 5-7 season that led to the firing of coach Brady Hoke. Fundraising is way down. By contrast, archrival Ohio State, despite rules violations that led to NCAA sanctions and a 6-7 season in 2011, is 76-16 during that same period, including 13-1 this season.

That sort of gap is unacceptable at Michigan, which is why the school was thrilled to have the chance to throw so much money at Harbaugh, a graduate who has been hugely successful at the college and pro levels. He is the Wolverines’ knight in shining armor, and no one much cares how much it will cost to feed the white horse or the knight.

The untold part of the story is this: For every program like Michigan, which can easily afford to pay a coach millions, there are at least four times as many schools trying to compete at the top level of NCAA football that are drowning in red ink. There are 128 schools playing at the Football Bowl Subdivision level. Perhaps half of the 65 in the power conferences are making millions each year. The rest break even — or worse.

The University of Maryland recently had to eliminate seven nonrevenue sports because it had so much debt — created by overspending on football. That debt also caused Maryland to bolt from the Atlantic Coast Conference after 60 years to join the potentially more lucrative (because of a better TV contract) Big Ten.

In November, the University of Alabama at Birmingham decided that funding 85 scholarships a year while drawing only 22,000 fans a game was no longer viable and shut down its football program.

Most schools that play football would save millions of dollars if they stopped playing football. But they aren’t the ones playing on national TV week after week. They aren’t Michigan, where paying Jim Harbaugh $40 million may sound obscene but, in fact, is a very sound investment.