People didn't believe negative interest rates were possible either.
Anyway, I bet at that level of loan the customer has a lot more power; no lender is going to want a billionaire to do their business elsewhere. The human lender who signs the loan gets a promotion for increasing the bank's future-money. And if it goes sour, that human won't lose money. Even the bank doesn't need to worry about its existence if it will be bailed out by the tax payer anyway.
Anyway, I bet at that level of loan the customer has a lot more power; no lender is going to want a billionaire to do their business elsewhere. The human lender who signs the loan gets a promotion for increasing the bank's future-money. And if it goes sour, that human won't lose money. Even the bank doesn't need to worry about its existence if it will be bailed out by the tax payer anyway.