That's a stupid argument, because none of the people on the richest people lists have any significant portion of wealth in liquid assets.
Wealth for good reason is not defined as amount of cash you own.
You seem to be replying as though I’m saying he’s not wealthy? Obviously he’s extremely wealthy by any definition. But most ultra-wealthy people are a LOT more diversified in their portfolio than Musk is. Someone with a diverse portfolio stands more chance of being able to functionally realise their wealth—if, say, they wanted to donate a large chunk of it to some charitable cause.
An argument could be made that Buffet is far and away the richest person (in terms of realisable wealth) due to his highly diverse holdings.