Not sure how credit cards work in Europe, but in the US, I use credit cards exclusively for the rewards they give out. I get 2% on all of my purchases plus an interest-free 30 day loan until my payment's due. I've never missed a payment and never carried a balance, so at the age of 24 I've made something like $3,000 net off of credit card companies.
I'm not sure about the rest of Europe, but the UK works pretty much like this. Lots of cashback, store vouchers or airline miles.
I guess the card companies win either way - in interest on people who rack up debts (enticed by the benefits) and also on transaction fees charged to merchants when the card is used.
I think with "I've never missed a payment and never carried a balance" you're not the tipical joe. I've read some banks can charce excessive rates when people forget (or can't) to pay.
