Tesla has made those people very rich. It has done x12 in the last 5 years, significantly outperforming the market (78% increase in that time), other big tech companies like Apple, Microsoft, Google, Meta or Amazon (who increase somewhere between 70%-350%). In fact, the only big company who has done better than Tesla has been Nvidia.
There is nothing particularly special about Tesla nowadays, and its shares, for better or worse, are linked to Musk's name. Him leaving Tesla would likely result in the company being in stock market just another car company, and thus the stock dropping to multiples of car companies, somewhere between 5-20 P/E instead of 56 P/E that is right now.