Interesting Personality

I met an interesting person once. Well, obviously I've met many interesting people over the course of my life and I anticipate meeting many more. But for some reason, I was reminded of this boy today, possibly because I heard another boy, probably about the same age, speaking as though he were a three-year old for a semi-extended period of time. This boy was annoyed that his mother was unable to pick him up and take him home until later, and consequently, he was whining in that sort of "it's not fai-yer... I want to go ho-me" whiny cadence, and complaining to anyone who'd listen
The boy who I met before was almost exactly like this. Everything had to be what he wanted at that moment. He used his parents' credit card to go shopping and spend hundreds of dollars on each excursion, he'd get people to drive him out to lunch where he'd get some gourmet lunch and coffee drink at least once or twice a week. He was very self-indulgent. And sometimes he'd be fun to have around because he could be very funny. In a way, he was like a local boy version of a valley girl, which proved at times to be hilarious. But other times, I could actually get a headache just from listening to him talk for ten minutes. He had an interesting personality.
What causes people to behave in this manner? As i think about it, I'v concluded that it probably has much to do with how one is raised and what types of behavior are deemed acceptable. If as a young child, whining got him everything he wanted and no real limits were ever set, this pattern of behavior could have carried on until the present day, or whenever they discover that that particular method of getting what they want no longer works.