Musk doesn't really care about the shareholders. He has a vision, and the company is the embodiment of that vision. The only reason he took the company public in the first place was for access to capital, and the ability for employees to sell stock.

Since the eighties there has been this maximal version of shareholder value, where the only reason for a company to exist is to maximize returns to shareholders. This was promulgated by private equity firms who would take over a firm and destroy many of the good things that a company was doing that didn't generate profits in order to increase returns to shareholders. Prior to the PE hostile takeover boom, there was a general understanding that shareholders were very important, but not the only stakeholder in a corporation.

If you invest in Tesla though, don't count on the corporate raider philosophy of stock ownership. They may have been able to get other companies in line with the threat of a hostile takeover, but Tesla has protective provisions that make it nearly impossible to do a hostile takeover of Tesla. For better or worse, Tesla is whatever Elon Musk wants it to be. If you're a shareholder, you're just along for the ride.