THIS. Elon is the largest Tesla stockholder, but he has taken out huge loans against that stock. If the stock price of TSLA falls below about $230/share (there is some confusion about the exact price, but it's widely believed to be somewhere around there) his stock could all be sold to cover the loan, which would suddenly dump the stock price even further, or he could be forced to post more of his stock as collateral for the loan. Either way, it's not good for him OR for the company.

Elon has used those loans to finance a rather extravagant lifestyle. He own FIVE mansions in Bel Air, all right next to or near each other. He owns a $70,000,000 private jet, a top-of-the-line Gulstream G650 ER, and flies everywhere with it, burning immense amounts of fuel sometimes just commuting within Los Angeles (between Hawthorne and Van Nuys airports, for example). Because his unusual compensation arrangement at Tesla is contingent on the company's increasing market value or maybe someday turning a profit (which has never ever happened), these loans against his Tesla stock are his main bread-and-butter.

In other words, Tesla's fate as a company and its stock price are intimately tied to Elon's personal financial solvency. That's gotta create some conflicts of interest between his various jobs as CEO, head of the Board of Directors, and a person who doesn't want to be personally financially wiped out.