Earlier quoted context omitted.
And meta's worth is much more than that. He's not personally paying.
A company being "worth" some amount doesn't mean it has that much money and real property; it means there exist people willing to buy shares, on the margin, at a price which works out like that. One of the common (very rough) approximations is that a business is worth as much as the profit it's expected to make over the next 20 years. But one of the reasons (there are many) that this is only a rough guide, is that if…
This common argument to not take market cap valuations seriously doesn't hold.
True, Meta as an entire entity is not liquid. A forced sale in entirety would produce a massive reduction in compensation. But that is a highly unlikely and contingent reduction.
It is also true that if you have Meta's equivalent in cash, the value of the cash is likely to drop, while the value of Meta likely to grow, over any appreciable time. In that sense, $X cash is worth much "less" than the $X market cap.
These seeming contradictions are the result of different practical tradeoffs in structures of wealth. Not because market caps reflect misleading or overstated accounting.