I have not used one since 2004. Went into rehab, and have not taken a loan since then, although I dip into the overdraft a lot still on the duff agency weeks especially. It’s paying to fill the car with fuel when you’ve got a flat 8 hour shift to get to 50 miles away that burns the money up. I avoid as much as I can, but sometimes it’s all there is, especially the first couple of months of the year, and right after Easter.
Credit card interest is an agreement between you and the lender. When you renounce (rather than “renage”) on that agreement, then all the money you’ve paid so far goes towards the so-called “defaulted debt”. Thus, if you borrowed say, £10k, seen it mushroom to £50k because of too long paying minimum payments, and the interest racks up, you might have already paid back £12k of it, in which case at the moment of default, there’s nowt the lender can do to get the rest back - the interest part that is. This is why they like to bombard you with letters saying things like “It’s not too late to save your account” or “Here are some spurrious charges for anything we can think of, but we’ve not put your account into default ourselves, lest you stop paying us the interest we make so much money out of”.
Consumer credit is like crack cocaine. Does no one any good that doesn’t have much money to start with. Its a get-rich-quick scheme that allows transfer of wealth from the poor to the rich, who expected to be paid handsomely for their millions sitting around in bank accounts, pretty much doing little to boost the economy. The current new boom-bust cycle has already started, based on fresh consumer debt all over again. The fact that it is a jobless/wage riseless recovery bears witness to this.

Either don’t take out a credit card in the first place, or default it when you’ve made enough payments to cover the original amount taken out.
This is how you enforce “I borrow at 0.5% interest rates” in the noble scheme of things. If you can, then do. How do you think commoners get to become kings if it’s not by saying “get lost” to those in authority at the time? - Screw it up though, and at least now days you don’t lose your head any more. 
When you borrow money, you do it with the idea in your head that somehow you are “going to be earning a lot more at some point in the not too distant future, which makes repayment inclusive of interest child’s play”.
News News! - It’s been some time indeed since ordinary workers knew they’d be better off 5,10,15 years down the line. Right now, we’re being sold the idea that “You’re better off if you’ve got a job in the future, rather than the zero hours/no job contract right now.” Are you?
You need both the job AND a massive catch-up pay rise that makes up for all the lean years (in one go) to put yourself properly in the “I can easily afford to repay all my credit with interest” category. That person is as rare as Red Dragons & Unicorns already.
If we all boycotted credit, then the cost of Living would come down rather than the cost of wages to employers. Oversupply of workers and credit forces up consumer prices and forces wages down, so ordinary folk get squeezed at both ends. Note the current government has a wide-open goal to prevent the 1st Jan 2014 influx of Romainians and Bulgarians from coming here. THey don’t need to shut the borders - just make it impossible to get credit & benefits for the first GENERATION (20 years) that new arrivals have both been here, and paid taxes. Thus, no good job lined up when you get here? - Nothing here for you my son! - This, in turn, would bring us in line with the rest of the world, so could hardly be called some “nasty” or “racist” or whatever policy.