Why does travel bring out the worst in some people?

Yesterday I saw a fellow passenger throw a tantrum at the lounge wardens because she didn't get her preferred seats. She was yelling so loudly that even through the doors between lobby and the main part of the lounge you could still clearly hear her. She was still going strong when I left to board my flight.

I'd like to say this was an isolated incident, but somehow there seem to be proportionally far more of these types of occurrences relating to travel than to every day life. I think some people get caught up in perceived entitlements and forget that travel is just a means of transportation.

The perks like being able to choose your own seat, or economically upgrading as a reward for loyalty, are not what really matters. The most important thing is to get from A to B safely, on a schedule that best suits and is affordable. Anything else is gravy.

Why do some people think its okay to be rude when travelling?