Credit card companies work in a way that - for some reason - people just don't understand.
They WANT everyone to have a long-term, low-level, interest-accruing debt. It's the best way to make a stable, long-term amount of money. They will literally lend to people that you, personally, wouldn't lend a coin to because they know they can pretty much always recoup that money over time.
They make NO money from people who have a credit card and just pay it off. The transaction fees are covered by merchants, etc. but they basically make nothing off those people. They just hope that, one day, something will happen and those people will become one of the above people, however temporarily.
They offer you incentives to sign-up. They offer you cashback. They offer you zero interest deals. They offer you balance transfers. Most of the time they'll actively make a loss on those (e.g. 0% interest means they have given you money and you pay back less money, even if the number is the same, because of inflation).
They want you to be in debt to them, and then they want you to treat that as a long-term thing because one day your boiler will fail or your car will stop working or you'll need money... and you'll use your already-approved credit card to pay it off and then they'll hope that you realise you can't pay it off in one go and start giving them a regular monthly payment. It's quicker and "cheaper" and easier than a loan, but a loan might be 5% and a card will be more like 25%. For the SAME THING.
They LOVE if you only pay the minimum payment. It's the best thing ever. Sometimes that translates to 10 YEARS OR MORE of debt to them.
They will take all that money from those in difficulty, accrue huge interest on it, and use that to spend on - basically - marketing. Giving the rich people an airport lounge pass, or giving you cashback on your burger, or whatever it might be. All that is just marketing to them. You tell people how much you get free on your card and your friends sign up, and maybe your friend isn't as good at managing their card as you are. Instant profit. Because what they spend on incentives is NOTHING compared to what they make from a long-term debt with a high interest rate.
They are predatory, and they're stinging those who can't afford it to fund millionaire's getting a free VIP pass or whatever.
If you're sensible, sure, you can balance 0% interest, balance transfers, etc. and even get free money from them. They don't care. They get enough from just the one person who CAN'T manage that, or who has an unfortunate turn of circumstance, because they will sting him 10 times harder to pay for you.
(e.g. I have a 0% interest on a card that I used to pay the legal fees to buy my house. Say I used it to pay 1000 whatevers. I only pay 1000 whatevers back. But several years later and in small increments. I transfer it whenever the 0% deal runs out and often pay a tiny one-off fee. My calculations say I've paid 0.35% APR on that amount over the last few years. You can't usually get a loan or any other type of credit another way for that APR. My last balance transfer was actually free.
If instead I'd just taken that money from my card and put it into savings, and I used 0% deals, I could make 4-5% profit a year without doing anything. Then use that same money to pay it back. Zero risk, all you have to do is remember the date at which interest will start being paid and pay it off before then. You could literally make money doing nothing for free, so long as your credit record was good.
Take out 10,000 whatevers on your card. Put it in your savings or investment account. Pay back the minimum payment from the 10,000 whatevers over time until you've paid it all off. Whatever is left in the saving account after you've paid it off is free money.
Do you think they do that out of the goodness of their heart? No. Some other poor mug is paying for that. Multiple times over. Once for you. Once for their marketing incentives. Once for the infrastructure to do it all. Once for their insurance to cover their risk. And probably 10 times over for sheer profit. And one day it could be you in that position if something goes wrong.
They prey on the weak by making friends with the strong.