Elon Musk's decision to smoke pot with podcast host Joe Rogan is the latest indication that his very public implosion may be irreversible at this point, says best-selling management author and CNBC contributor Suzy Welch.

"This is not just a genius acting out anymore. He's forgotten that his job is to be a leader."

"It's like watching someone go somersaulting down a staircase," Welch adds in a phone call with CNBC Make It.

Welch called the situation with Musk "very sad" on Twitter on Friday.

Welch on Twitter

"As a person who has spent her career thinking of what makes a person a leader," Welch explains, she finds the spectacle of Musk's behavior "deeply sad." He is, after all, "a great genius," she says, "a visionary." The problem comes when geniuses and visionaries start "believing all the stuff that's written about them." At that point, they're no longer "governed by humility. They start to believe they're a prophet."

And unfortunately, as history shows, "very few people who think and say they're prophets actually are."

In short, "he jumped the shark," says Welch. Once you start thinking you're "untouchable," connected to a higher power, "you lose all your governing ability."

Strong leadership requires that a person remain grounded, willing to do the unsexy grunt work of running a company. That's why Musk's current erratic behavior has unfortunate implications for his company, its employees and its shareholders, as well as his family, she says.

A few hours after Musk's interview, Tesla announced that its chief accounting officer was leaving. He tendered his resignation last week, but Tesla just announced it on Friday. Shortly thereafter, Tesla's HR chief said she was leaving as well. Those executive departures, coupled with the Musk interview with Rogan, led to Tesla's shares falling as much as 9 percent.

The executive exodus shows that even employees think Tesla "may be past the point of no return," says Welch.

Welch herself is not an investor in Tesla, though she appreciates and admires the products, which she calls "beautiful and exciting," and she's rooting for the company's success. How many entrepreneurs, after all, can do well by doing good? That's rare.

Still, she says, as someone who could put money in the company, the chaos is a turn-off, "absolutely."

"It's a very dangerous combination, when someone wants to be a prophet and a celebrity," she says. He can be a genius, he can be a visionary, he can be a celebrity, but the only person who's ever really succeeded in being all three, she says, is maybe Oprah. "Everyone else ends up like Icarus."

Tesla declined to comment on Welch's remarks.