Why would you pay a yearly fee to use a card when I can use my debit card for free, not have to worry about paying off a balance monthly as its coming directly out of my account, nor have to deal with having yet another item in my wallet?
Less cards simplifies life. I laugh at those people who have 3-4 credit cards in their wallet and have to think about which one to use. No sir. If I don't have the money in my account, I don't need it for smaller purchases. I'm not including my vehicle or house for obvious reasons.
Simple. Because you save TONS of money. If I have multiple cards (which I do, and I have no fees on any of them), I have 1-5% cash back on everything. If I save 5% on gas, I'm getting gas at a cheaper price than the cash value (Assuming that the prices are different, which is pretty rare in my experiance these days)
I just paid for a 600 dollar flight COMPLETELY through credit card rewards. The flight was 100% free because I got it through my rewards.
Most cards don't have fees. Even the ones that do, the idea is that if you use it mainly, the cash back will pay for it, and even if it doesn, the laudry list of passive benefits you get is more useful than 75 dollars a year.
I have never paid a single cent in interest or fees, everything I buy with my card is something I can afford. Then every once in a while, get a free flight somewhere to my liking.