I do not think he is the richest man in the world, and think someone whose name I have never heard probably is, although I doubt they hold their assets in their name. However, as you point out reckoning of wealth on the basis of assets requires a balance sheet that includes liabilities, and I don't think any wealthy folks capable of reason provide such information to gossips.

As you point out, the common trick of borrowing against collateral could well have run the Elon aground on the reef of a ~20% decline in his assets' price.

What I find more notable is that the Elon has murmured not a peep about it, seems to be making no moves to staunch the hemorrhage, and that after news has come out Trump removed the green subsidies for electric cars, which was Tesla's biggest profit generator. This lends the Elon an appearance of altruism which is very difficult to discount. Folks not concerned nor familiar with the extent of his feeding at the public trough with Spacex's MIC contract work might even think him a saint because of it.

Thanks!