Because a lot of Tesla early adopters bought Tesla cars to support Elon’s plan. In the early days there were a lot of quality issues, inconveniences (waiting months for parts etc.) early adapters were willing to overlook because people genuinely thought Elon was trying to save the world. In the present day, there are a lot of better alternatives if you want a greener car. Much smaller EVs and EVs from traditional car makers that have decades of experience in quality assurance and quality control. So if you’ve become disillusioned, there are a lot of reasons to sell a Tesla.