[dasil003]

You don't have to be in debt, paying your credit card in full each month is an excellent way to build credit, and you will never pay a cent in interest as long as you pay in full without fail.

I can see how it all appears to be a silly game if you never actually need credit, however there are material benefits (cash-back, rental car insurance, etc) of playing the game. In some cases the benefits you receive are nonsensical until you realize they are subsidized by irresponsible individuals paying huge sums of interest. There's a special kind of smug pleasure reserved for those who are financially responsible in America.

[johnchristopher]

Can you cancel your credit card at any moment if you know you are going into a tight spot soon ? So you don't enter the vicious circle.

[dasil003]

Sure, although the age of credit accounts is a significant factor in your credit score, so it's not advisable if you are trying to build credit.

Personally I have enough practice that I treat my credit cards no different than I would treat my checkbook—it's not that hard to avoid trouble if you just have the mentality of only spending money you already have. In other words, I personally don't think cancelling the credit card is necessary, but YMMV.