The main problem with credit cards, is of course, that all your purchases are "tracked". The other bad thing, if you travel a lot is, they are almost a requirement for the airlines, hotels and car rental. In fact, as far back as the early seventies, believe it or not, when hardly anybody had credit cards and when my family was in a car accident in Wisconsin, the car rental place wouldn't even rent my father a car unless he had a credit card. Eventually he was able to use his work id, and driver's license which they called and checked out, to get us a car for a few days.
I've got one credit card, believe it or not, that I have to drop that still charges a small annual fee, and I am a sucker to pay it since I have other cards. Unfortunately, this is the only card that I have memorized all the numbers and the expiration date, so I can use it to purchase things, at least over the phone, even without the card in hand. Since I've held this card the longest, it also has the largest credit line.
Note to self: Memorize the numbers on another card and drop this one.