The Bellagio was quiet save for the industrial vacuum cleaner an employee pushed over the carpet. Across the casino, Jim Buss cut a solitary figure in front of an otherwise unattended bank of KISS-themed slot machines. The Lakers top basketball executive sat alone with his thoughts, credits in the machine and his customary pack of Newports.

It was 4:30 a.m. during the Las Vegas Summer League of 2015, and the sting of free agent LaMarcus Aldridge’s rejection of the Lakers was fresh. Black cap resting on his head, Buss, who lives in Dana Point, grew more agitated and defensive as he repeatedly mashed a lighted button, waiting on the long odds that Gene Simmons’ painted face would line up three times in a winning combination.

Fired Tuesday amid the Lakers’ fourth straight losing season, Jim Buss lamented that night in Vegas that he had told Aldridge joining the Lakers would make him the biggest star in the world. The forward had made the wrong decision. And yet Buss was the bad guy? He was incredulous.

An exasperated Buss, confident even as the franchise crumbled around him, exclaimed, “I will have the last laugh.”

It was almost unbelievable, this horse trainer miscast as a hoops executive uttering a line typically reserved for central casting villains. On Tuesday, there was none of the laughter Buss promised, just the ear-to-ear grin of Earvin “Magic” Johnson as he vowed to deliver on the same promises that Buss could not.

Sweeping changes were made to an organization with 16 NBA championships, as Jeanie Buss not only removed her brother from power but fired General Manager Mitch Kupchak, who oversaw five championship rosters. Even longtime public relations executive John Black, closely linked with Kupchak, could not escape the massacre.

The next man up is Johnson, who is rich in charisma but short on experience. He was not sheepish in his first day on the job, shipping Lou Williams to Houston for Corey Brewer and a coveted first-round pick.

Rob Pelinka, Kobe Bryant’s agent, is reportedly in line to join Johnson as general manager, following a path forged by Golden State’s agent-turned-executive GM Bob Myers.

“I’m putting it all on the line,” Johnson said when asked what the job could mean for his reputation as an L.A. icon. “I knew that when I signed up for it.”

The same could be said of his new boss.

This was Jeanie Buss’ move to rescue the organization she was entrusted to oversee. More than a bloodless coup by Johnson, it was a stone-cold power play by Jeanie Buss. Anyone who questioned whether she was tough enough to fire her brother has been silenced. She is front and center atop the Lakers organizational structure; no more twin spires of power.

She made a mistake letting her brother and Kupchak flap in the wind while Johnson spent a couple weeks blustering to anyone who listened that he was coming for their jobs. She remedied that, however, by making quick work of the two executives.

From a legacy standpoint, this is a make-or-break moment for Jeanie Buss, who, with some success, could become the first female NBA executive enshrined into the Naismith Memorial Basketball Hall of Fame.

There is no such Hail Mary for the second son of the late Dr. Jerry Buss. He hung himself with his own three-year timeline.

The narcissism Jim Buss displayed that long-ago night in Las Vegas was a microcosm of his fatal flaw. This was a man who saw no irony in using the main theme from “Man of La Mancha,” as the tone that greeted anyone who dialed his flip phone.

“I love all plays, basically,” Buss once said. His previous ringback tone was from “Phantom of the Opera.”

“Man of La Mancha,” he said, “is one of my favorites.”

The reclusive Buss should have learned from the musical adaptation of “Don Quixote” the dangers of tilting at windmills.

He criticized disinterested free agents like Aldridge when he should have changed strategies. He feared the specter of Phil Jackson, whose rumored return was dashed when the former coach and Jeanie Buss called off their engagement in December.

As the bridge to the next Lakers empire became more complicated, Buss’ circle grew smaller and smaller. He was rarely seen without Lakers scout Chaz Osborne; his very own Sancho Panza.

He and Kupchak insulated themselves from dissent at a time when they should have listened to a symphony of voices. Instead, they doubled down on a curious plan, investing heavily in mediocre veterans Luol Deng and Timofey Mozgov last summer, leaving the Lakers with room to recruit only one maximum-contract player next summer.

Buss felt the pressure from the outside to perhaps an unhealthy degree.

It became apparent to some within the walls of the team’s El Segundo headquarters that the two executives were operating out of fear they would lose their jobs rather than in the best long-term interests of the franchise.

Now Kupchak is unemployed and Buss is just a part owner. Jeanie Buss fired him from his post, not his equity.

She knew this day was coming. Jeanie Buss had leaned on confidants, seeking guidance on how to reinvigorate the wayward franchise. And when she got to Johnson, he told her what she wanted to hear.

“One thing that happened here is that the Lakers have been losing,” Johnson said Tuesday, “and we made critical mistakes. It’s not like anybody wasn’t given a fair shot at this.”

That did not make the decision to fire her brother, whom their father desperately wanted to succeed, any easier. It was so difficult, in fact, she acknowledged Tuesday that she “probably waited too long” to make a change.

“For that,” she told Spectrum SportsNet, the team’s television partner, “I apologize to Laker fans.”

The onus fell on Jeanie. Her brother was never going to give up his seat any other way, not while he still had credits left to play.

Contact the writer: boram@scng.com