So why isn't the suggestion to tax the loan instead of the asset (that is 10x more volatile than say property)?

That may be a perfectly viable solution. Seems like an easier path to me, at least. But the point is that these assets are a lot more fungible than you imply.

> It is not a good measure of the money someone may be able to realise.

And as such, when you get into the higher ranges, net worth is quite a good indicator.

I think it’s exactly at the higher ranges that you are more likely to run into concentrated positions where valuations are not simply a total value multiplied by a percentage ownership.

What is Cargill “worth”? Suppose the families announced they were selling 90% of it on Monday. Would they get that figure?

What is Jensen Huang’s share of nVidia worth? If he announced he was selling all of in October, why would he not end up with that figure?

It’s quite different for a bank to lend Jensen (or Larry Ellison or Elon) 5% of that notional figure. They don’t need to care whether the true value is 30% or 50% of the notional to make that loan.