But that's not it.
Shares came under pressure at the opening following the Musk online interview and news that chief accounting officer Dave Morton was leaving only a month on the job, citing the company's frenetic pace. Musk smoked what Rogan described as a joint containing a mix of marijuana and tobacco.
In August he told the New York Times that he worked "120-hour weeks" and took sedatives. Musk asked his host after he took out a large joint and lit it up. According to CNBC, Morton felt Musk and the other executives didn't care to listen to the financial obstacles involved with taking Musk's tweet seriously.
"Since I joined Tesla on August 6, the level of public attention placed on the company, as well as the pace within the company, have exceeded my expectations", Morton said on Friday in a statement included in a filling with the US Securities and Exchange Commission.
Tesla shares sank 6.3 to close at $263.24 after the latest events that heightened concerns over Musk's erratic management style at the electric carmaker.
Then, like a nervous teen trying to fit in with the cool kids in an outdated after school special, Musk exhaled before the weed smoke could touch his lungs, employing President Bill Clinton's famed anti-inhalation method.
"It's very hard to keep a auto company alive", Musk told the interviewer, just one of many unconventional statements he made that likely spooked investors.
And indeed this may not strike many as all that daring or risque, but remember that Mr. Musk is the CEO of a multi-billion dollar publicly traded company. His responsibilities could include the types of things analysts have said Musk needs a COO to do in running the day-to-day operations of the company.
Musk told The Guardian in response to a question about whether Tesla drug-tests employees that "our policy allows trace amounts of THC [an ingredient of cannabis] during work times, provided they are below the safety limit (much like a minimum alcohol level)".
Morton joined the electric vehicle company the day before Musk tweeted that he was considering taking the company private, causing stocks to soar and prompting and a Securities and Exchange Commission investigation from over whether he had funding secured, as he had stated.
"It's time for Tesla and Elon Musk to grow up", said Michelle Krebs, executive analyst at Autotrader.
"The team, the skill set that have been phenomenal to create Tesla are not the ones we need for the next stage", said Houchois, who has a US$360 price target on the stock.
Back in April 2016, Air Force awarded Musk's company with almost $83 million to launch a GPS III satellite, and extended contracts in the following years. I believe it is fine if it is done responsibly and appropriately and I am pleased that it is becoming legal in many states around the country.
Musk shrugged but said nothing.
Especially freakish moments involving the Tesla chief of late include disparaging remarks about Vernon Unsworth, a Briton who helped save boys trapped in a Thai cave and the abrupt shutdown of Wall Street analyst's questions during a contentious earnings conference call.