What always gets me about money is this:

There seem to exist (at least) two kinds of money, although we call them both money and we expect them to work the same.

One kind is the one (presumably) you, I and everyone I know deals with. You have to invest a lot of effort into obtaining it, it's important not to waste it and if you run out, there won't be any fresh milk at the end of the month. If no money is coming in after that, there also won't be a fridge or a place to keep a fridge in.

Then there is this other kind of money. It is (as shown in the paper above) simply brought into existence whenever someone takes a loan, even though there is no law actually allowing the bank to perform this numeric magic. "Airmoney" is added to your account and you're expected to pay it back... with interest and compound interest. Since you aren't allowed to conjure money, that interest needs to come out of your "work money". If you don't pay, the bank gets to take away everything you own. If you do pay it back, the money which was originally loaned to you is destroyed in the process but Mr. Bank gets to use the interest to pay for the goods and services you produce. Or to buy an island or two.

We consider this normal.