At the moment many governments, such as Finland's, are able to borrow money at negative interest rates. My question is: why don't they borrow as much money as possible while interest rates are negative?
The answers I have heard so far don't make sense.
Governments avoid borrowing too much money because that would lead to spending more money
This doesn't make sense: they could borrow money and not spend it and just take the profit from the negative interest rate.
Governments avoid borrowing too much money because they want to minimize the risk that a bank fails and loses their money
This doesn't make sense: they could take the money out as cash, pay people to guard it, and still make a profit from the negative interest rate even if the money was just sitting in a safe.
Governments avoid borrowing too much money because there are limits to how much they can take out in loans in they won't to keep a healthy distance to those limits.
This doesn't make sense: if they borrowed money at a negative interest rate now, and just saved the money, they would be in a better position in the future compared to not taking the loan. (In all cases except when interest rates go even more negative in the future, in which case it might be beneficial to take the loans when the rates are lower - however, no-one is arguing that governments would be speculating like this).