Same, I use them because my regular bank are a bunch of muppets when it comes to mobile payments. I use Klarna to pay with my phone. It auto debits from the bank account. I've never paid them any interest. Works fine, other companies are available offering similar services. Key for me: works online/offline, sane process for blocking things, works internationally without getting ripped off on exchange rates, etc. I guess they make some money on deferred payments to vendors. Good for them.

You can choose to go into debt with them and they make that really easy. But it's a choice in the end. If you can't be trusted running your own finances, don't get a credit card from any bank.