[kazinator]

> Why should a credit card company get a 15-30% return on their investment each year?

That is simply not correct. Credit card companies get much, much more return on their investment. They get free money from collecting merchant fees from every transaction, and from credit card annual fees.

If we regard the "investment" as the marginal cost of setting up yet another new merchant or credit card user, the return rate is just ridiculous.

You issue a cheap, little plastic card to someone, and get $100 per year from them, plus several percent on everything they buy. And that's if they always pay their bills on time.

(They give you that $100 willingly because out of that several percent take, you kick something back to them, which ends up adding up to more than $100 over a year.)