The intersection of sports as an emotional escape and sports as a cold-hearted business is as volatile as the crashing of hot and cold air masses in the sky.

The collision can, under the right circumstances, create a storm destructive enough to alter a landscape.

In sports, heroes quickly become villains, regardless of their intentions. It’s almost impossible for us to walk a block in their shoes, nevermind a mile, to understand the motivations behind their decisions. To us, leaving the hometown team is a crime, and the betrayal of leaving to join a rival is the most unforgivable of sins.

Hackles still rise at the mention of Ray Allen, who, to many, will be the most traitorous of traitors who dared turn coat and run from here. Nevermind that he was told he’d been traded only to have it fall through. It doesn’t matter that his role had been reduced.

Allen dared to join LeBron James. He left without saying goodbye. And now he’s forever a pariah.

The rivalry with the Philadelphia 76ers is historic but not nearly as intense as Boston versus LeBron James in the mid-aughts, so Al Horford becoming a Sixer may not sting quite as badly as the Allen departure did. The facade had already begun to crumble around Horford, so his decision to leave is easier to comprehend.

It still stings, though, and Horford is testing the limits of Boston fandom. The Joel Embiid-stopper is now becoming the Embiid-helper, which robs Celtics fans of the one thing they could always dangle over the heads of Sixer faithful.

No matter what Philadelphia did, no matter how many stars they signed, Boston had Horford and they didn’t. Boston was always the team uniquely built to give Philly fits; to be that roadblock that made them wonder “will this process ever truly pay off?”

Now he’s one of them. The Sixers paid a big price, but they didn’t just add Horford to their team. They took him away from ours. They aren’t just adding one of the league’s most respected professionals, they’re performing a Horfordectomy on Embiid’s brain.

Horford’s steadying hand will be very welcome in a Philadelphia locker room which has dealt with some explosive personalities. Combine that with the subtraction of Jimmy Butler’s notoriously gruff attitude and the Sixers will have a level of stability they haven’t seen in a long time.

There’s no getting around how tough a loss this is for Boston. Horford was the reason why Boston could sustain so much damage and keep advancing in the playoffs two seasons ago. His presence is what helped so many guards around him have career seasons year after year. And if you’re upset at how this past season unraveled, imagine how quickly it would have happened without him helping hold things together.

There is no replacing Horford, no matter what the Celtics cap situation is. There’s no exception big enough to find a player in the league that can play on the perimeter or inside as well as Horford does. He is the collateral damage of a season gone terribly wrong, and it’s going to take the Celtics a long time to recover.

It’s going to feel even worse when the Sixers come to town and Boston has no answer for Embiid. It’s going to be very painful watching Ben Simmons get dunk after dunk because of the space Horford opens up when they run the pick-and-pop.

Sports fans boo opponents. That’s part of the performance aesthetic, so there isn’t much room for nuance when the costumes are on. Our colors are good, their colors are bad, and that’s that.

Horford blurs those lines just a little, though. He was willing to stay in Boston, but things fell apart. He was presented with a windfall that most 33-year-olds don’t get, so he took it. He’s made a lot of money in his life, but this contract could nearly double it.

It’s hard to be mad at that business decision.

But civic pride creates strong emotions. Boston isn’t just the name of a team, it’s an identity. People grow up rooting for the jersey, no matter who fills it. Winning makes fans feel good about where they live, and anything that takes that away amounts to a sort of personal attack.

This is why fans say things like “we won.” There are 41 guaranteed gatherings at the TD Garden of 18,624 people, most of whom show up wearing team colors in solidarity with the men on the floor. They share in the highs and lows, riding the twists and turns for two-and-a-half hours before leaving experiencing some kind of strong emotion.

It creates a bond that fans wish players could share.

“Please love my city as much as I love it!”

You would quit your job right now if Danny Ainge offered you a million dollars to wave a towel at the end of the bench, so it might be hard to comprehend why a guy who is already set for life would seemingly turn his back for a few extra million.

Who needs it, right?

The business of sports turns humans into commodities. They are discussed and traded like stocks. Teams value them until they are no longer valuable. Most players don’t get to see their careers end with Dwyane Wade or Kobe Bryant-like farewell tours. Most end up getting cut; discarded like litter and forced to face the harsh reality that no GM’s are going to call their agents anymore.

So players are forced to commodify themselves.

Horford didn’t need more money in this contract, but the dynamics of the sport demanded that he take it, even from Josh Harris.

There’s no doubt it will cause a storm of criticism. Horford is now the enemy to many, the same as all the other so-called greedy athletes who took the money and ran. Fans have every right to this emotional reaction. That’s sports.

But it’s also business, so in a way this is a fitting end. The most business-like player the Celtics have had in recent years is leaving town, and he’s doing it by making the most business-like decision a player can make.