Why do people not queue up?

Why do some people refuse to queue? I was at 7-Eleven and there were about 4 people in the queue at the check out counter. One guy came in, saw that there was a queue, went straight to the counter and asked for a pack of cigarettes. Thank God the check out clerk ignored him, and he just left. So why do people not queue up? Is it because...

• They think they are more superior to others and consider everyone else of lower cast?
• Their time is so much more precious and it's ok for everyone else to spend that extra time spent on them?
• They want the additional attention when they get the stares?
• They never learnt the concept of queing, so it's really a survival skill of the most aggressive person being attended to first?
• They simply do not care?
• They are simply STUPID!

By the way, the last point is a statement rather than a question.