[throwaway173738]

Valuations are often an absurd fantasy. The notion is that Musk could find a buyer who would be willing to pay that based on the value of each share he owns. It’s not real money. He can borrow against it but not too much, and he will have to find a way of paying the lender back without selling stock. The money is not real.

If he dumped all of his shares the value of them would essentially go away, like with any commodity.

[inigyou]

He gets to exercise power based on his valuation, and in that sense, it is real. He is now known as the world's richest person and first one point five trillionaire, even if he doesn't have one point five trillion dollar bills in his closet. He gets people to suck up to him for fractions of it - "do X for me and I'll give you shares worth a million"