Overstock's ex-CEO loves crypto, calls Warren Buffett his 'rabbi,' clashed with Mark Cuban, and dated a Russian spy. Here are 5 wild facts about Patrick Byrne.

Byrne has squabbled with Mark Cuban, the "Shark Tank" star and owner of the Dallas Mavericks.

Byrne told a Bloomberg TV host in 2015 that the billionaire's friends were trying to get federal authorities to investigate him.

"Some of the officials are monsters," he said. "You'll probably read a headline that I was stopped with drugs or a dead body."

"Patrick Byrne is a paranoid fool," Cuban responded on his blog. He added that he had shorted 20,000 Overstock shares and "would love to short many, many more shares" because "companies run by people I feel are paranoid fools, tend to go out of business."

If he wanted to sink a company, he wouldn't go to the authorities, Cuban said. "I would just try to get them to hire Patrick Byrne."

Byrne fired back in an interview with a Business Week reporter in early 2006.

"Mark Cuban is living proof that even the billionaires club has a bell curve: Mark holds one end of it, and Bill Gates has the other," he said. "You guess which is which."

Byrne accused a "master criminal from the 1980s" of coordinating an attack on Overstock in 2005. He labeled the individual a "Sith Lord," the title given to Darth Vader and other villains in the Star Wars franchise.

Byrne doubled down in 2006, suggesting "Al Qaeda" was a more accurate description for the people conspiring with the US government and the media to damage his business.

In an interview with the New York Observer in 2010, Byrne revealed the targets of his insults were two well-known financiers. "It's Steven Cohen and Mike Milken."

Cohen is the billionaire founder of SAC Capital, who now runs Point72, another hedge fund. SAC pleaded guilty to insider trading charges in 2013.

Milken helped to develop the market for high-yield or "junk" bonds. He pleaded guilty to securities and reporting violations in 1990, and spent two years in prison.

Byrne sold at least 1.7 million shares in Overstock for more than $30 million between September 2018 and May 2019.

He planned to use the proceeds to add to the $12.5 million he's already invested in blockchain projects, and finance the roughly $50 million he's pledged or already given to charity, Byrne said in an open letter in May.

"I simply had to supplement my nominal salary with stock sales in order to fulfill personal commitments to invest personally in blockchain projects" and meet his charitable pledges, he said.

Byrne was bemused by the backlash from investors to his stock sale.

"Frankly, I had no idea that shareholders would demand explanations of why and how I might want to use my cash derived from my labor and my property to pursue my ends in life," he said.

Byrne was romantically involved with Russian spy Maria Butina, her attorney confirmed earlier this month.

The Overstock boss claimed in multiple TV appearances that he served as a FBI operative in the run up to the US presidential election in 2016. The agency ordered him to maintain his relationship with Butina, who he met at a conference in 2015, he said.

Byrne claimed in a statement that he helped the "Deep State" and the "Men in Black" — the FBI — to conduct "political espionage" against Hillary Clinton, Donald Trump, and other presidential candidates.

"I now plan on leaving things to the esteemed Department of Justice (which I have doubtless already angered enough by going public) and disappearing for some time," he added.