The entire point. Even in his offer he basically gives a "the deal must be exactly this or I will have to sell all my shares". He's already selling his shares. He's pumping a premium before then and building his brand.
I've been impressed by his ventures at SpaceX even though
@Filthy says I shouldn't be. But it's probably that I'm not very educated on the space...of private space.
But to answer your question, because a bunch of incel bros think Elon is their billionaire friend. Elon has to pay some taxes and doesn't have the cash to do this. He makes a Twitter poll claiming the poll outcome will be the reason for him selling off a portion of his Twitter stock. He already had to sell some to cover his payments since he doesn't have the cash on hand. He couches it in the topic of taxes on his assets held to show how little he cares about money and his lap dogs eat it up as a flag of populism.
Elon sues people to claim founder status of companies he didn't found. He sues and personally attacks anyone coming for his own brand building. He's terribly concerned with image and money as the two are inextricably linked in his setup and future value.
But still, despite publicizing risk to subsidize his company then maximally privatizing profits, people champion his altruism through business... despite the repeated anti competitive moves and vaporware as a product. He's just another businessman driven by the same accumulation goals. He is more adept at most in image management.