That is one of the ways they avoid taxes. They take out loans to pay old loans and to spend on the value of their investments at good rates, and since they never realize income they never pay taxes. I think interest is even tax deductible to a degree.

Bezos in 2020, a year his wealth multiplied obscenely, paid 600 dollars. Less than we did.

As per a couple of propublica articles they published around 2021.