Short answer: because when it comes to stock market, people invest in future of the company, not its present. And Musk is unpredictable. Tesla only car allowed

Short answer: because when it comes to stock market, people invest in future of the company, not its present. And Musk is unpredictable. Tesla only car allowed to drive on Mars? Why the heck not?? Who knows. People been investing in Tesla for many years now and barely were ever disappointed unless you were shorting the stock in which case when expiry date came (futures) many were taking second mortages to clear their calls. There is too much money on the market for enough people needing to exit Tesla stock and enter something else that would possibly give them better gains over next 5-10 years, so they hold long term, making less stock moving on the floor and giving it longer stretch.