Self Centered Lane Dodger

I was on my way home from work, driving on the expressway. Traffic was moderately heavy, but all said and done it was moving at about 65 MPH. I was cruising in the left lane about 30 feet behind the vehicle in front of me. All traffic in the left lane is moving notably faster than the right lane. Suddenly this clown comes flying up the right lane and squeezes into the space in front of me, completely eliminating my buffer zone between myself and the person in front of me. I proceed with my current speed, not allowing the perpetrator who just cut in front of me any breathing room. I could tell he was getting nervous because first he started slowing down giving a little separation between him and the person who was in front of me before he so rudely cut in. I've got a pretty iron resolve when it comes to people that do this sort of moronic thing and I didn't offer him another foot. He then decided it was time to start braking. Okay, so lets go over this:

~ I'm driving 65 MPH as is the vehicle ahead of me and behind me
~ There is 30 feet between us
~ Moron flies up right lane and forces himself into that space
~ Moron slow down but I do not give way
~ Moron brakes causing chain delay in traffic flow

So! This idiot had to cram himself into a space that was barely large enough for his car and then proceeds to slow down, in turn forcing me and the drivers behind me to slow down too.

What is the purpose of this action?
Is he trying to slow traffic down?
Is he trying to cause an accident?
Is he so self righteous and self centered he can't see what he did wrong?

Just another of the dozens of bone headed moves people make every week to continue to add to my aggravation while using our fine roads.