Why is this even a question lmao
user
The problem is 25% of what?  Most billionaires don't accumulate their wealth from income it's from unrealistic profits of stocks they own.
assistant
Agreed, this is just a fantasy to make people feel better. You have billionaires making $1 in normal income and then they take out loans dirt cheap against their perceived value and stocks to double dip the system to pay for their lifestyle and other investments.
user
Unrelated but are there anytimes where these loans backfire on banks? 

Where the person taking out the loan just becomes worth 0 on paper overnight?
assistant