I disagree with Douglas. They do not "Prey" on consumers. The consumer pulls out the credit card and uses it. Yes they may offer you a free t-shirt or some cash incentive, but that doesnt mean you have to use the credit card. The consumer needs to realize that they have a contract with credit card companies. If you pay your bills on time, you dont overleverage yourself, you wont have a problem. The problem is, consumers dont realize this. If you put 10,000$ on a credit card, you assume a risk that they could raise your APR. So if you choose to do that, you should have a means of getting around any fee increases.
Lets look at it from the credit card companies perspective. They loan you money which is not secured. If you default, after 90-180 (I believe) days, they have to write that debt off as a loss and sell it for pennies on the dollar. So for example, we have 5 people who all have 10,000$ on their credit card. The APR is 20%. If all people pay on time, the company makes 10,000$ per year. From interest. But 1 person defaults and doesnt pay. This means they lost 10,000$ (maybe could recover 100$ from the debt sale). Well now they are making 8,000$ off the remaining 4 people, which means they have a 2,000$ loss. What should they do? Raise the APR. This is why our rates are staggered on credit ratings. People who dont default are less of a risk, people who do default or look like they could default, are a higher risk.
Its all math, they arent "Preying" on the consumer. They have the right to make a reasonable profit on their loans. The fees are another issue. The fees are used (Late payment, over limit) to offset the loss on defaulted accounts. As the account ages in default, these fees accrue and allow the company to write off a larger number as a loss for tax purposes. They would loose significant profits if they could not do this.
I would also argue that Credit Cards DO NOT lead to financial trouble. Peoples spending habits lead to financial trouble. People have simply overleveraged themselves calculating their maximum credit utilization by what minimum payment they can afford will have problems.