The child tax credit starts tapering off if your adjusted gross income is more than $200k single ($400k joint). If Bezos is reporting less than that due to other deductions then that’s truly impressive.
Edit: also you need to pay the loan back, and the income to pay it back is taxable. You can die with an outstanding loan, but i’m sure bezos lenders will structure the loan to make sure they get most of their money back.
Bezos probably has an army of banks, private lenders, and private capital connections to effectively have a lifetime of loans against his Amazon shares.
It's a pyramid scheme, except the guy at the top actually has the money and collateral.