What's the average interest rate for a credit card or a "buy now, pay later" loan?

For credit cards, it's 18%. For "buy now, pay later" loans, it's 23%.

Inflation is currently above 8%. Many companies' profit margins are below 8%. But for $V $MA $AXP $DFS $AFRM $SQ $PYPL etc., they're already making a lot more on each loan. Many banks envy these fintech companies.

Mortgage rates are surging, but at the same time, their rates haven't been as high as what the credit card companies and BNPL loan providers charge.

As for the % of people that pay their credit card and BNPL balances in full every month, it varies. For credit cards, it looks like 1/3 of users pay their balances in full each month. For BNPL, that number looks to be a lot lower because the credit quality of those that use BNPL is lower too. In general, the majority of their customers accrue interest in those companies. It explains why those companies are highly successful today.