Of course, if that value drops you’ll get margin called for more collateral
Unaccredited investors (us, commoners) have access to margin loans for up to 50% value of account.
Accredited investors have access to portfolio margin which can be up to 90% of mark to market value.
That’s nothing to say of any custom financial instruments that banks might come up with to save bezos any taxes. Think swaps.
Of course, if that value drops you’ll get margin called for more collateral