What can this person possibly be thinking?

As often as I see people either on TV or in real life making scenes and public nuisances of themselves, I never cease to be amazed. I can understand the traveler who has come to his limit of delays and problems at the airport and has finally snapped. I am not referring to people who have reached the breaking point.
I refer to the people who are looking for a reason to start problems with either the people near them or the hired help in whatever establishment they happen to be.
From the ridiculous bad behaviour we see on the news and reality TV especially to the loud name calling and attention drawing spectacles in my daily life, I always wonder; What is going through this person’s mind? What do they hope to accomplish?
Many of them are looking around the whole time, either for support or just to see who is watching. Even the non confrontational ones who just feel the need to be more “in” the room than anybody else and engage others loudly and boisterously.
Are they just keeping track so they can brag to their friends later? What is going on in their minds? Have you ever confronted anyone like this or had to deal with them?