It’s really simple. Loans don’t count as income so you use your stock to get guaranteed loans. And you don’t take most of your income on a W2 you take it in stock.
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.