One of the reasons these people have low income i.e. poor jobs could be because they dont have much common sense.
These people are generally very quick in asking for increases in limits. They regard the limit as a target and once they reach it, they need a higher target. I dont think it ever occurs to them that they have to pay it all back some day.
I would agree that a lot of these people are very unhappy - wouldnt you be if you were stuck in a low paid dead end job with no prospects. These people have very little to look forward to in their day to day lives.
One behaviour that I've noticed is that low income people live in 2 x 6 month cycles. They spend 6 months of the year preparing for and talking about their summer holiday - usually some cheap resort in Spain etc. and the other 6 months of the year preparing for and talking about Christmas. Their lives are so bad that all they have to look forward to is these two annual events. They are the types who book their holidays in January and start chrismas shopping in September. They spend 6 months of the year in "holiday clubs" and the other 6 months in "christmas clubs".