As a rider myself, I know exactly why this biker did what he did. It was done out of pure frustration, and certainly a bad decision, but what the car driver did was a criminal decision. I run into bad drivers just about every time I'm riding, and it gets extremely frustrating. Just yesterday I was making a left turn, and as I'm sitting in the middle of the intersection waiting for the oncoming cars to pass so I can finish my turn the light changes and as I start moving some t#at in a huge SUVs starts moving right at me without letting me finish turning. I had to start honking and yelling at him to get his attention, and in the meantime the cars from the other direction also start moving. I'm sure this has happened to just about everyone who drives, but when it happens to you when you're driving a car its just frustrating, for a biker it is frustrating and gravely dangerous.

It's very weird how seeming normal and respectable people turn into complete a-holes once they get behind the wheel. Driving aggressively, honking, cutting in and out, not respecting the rules of the road, not yielding to pedestrians while making turns, having no patience, etc. As a pedestrian I once kicked a car that didn't yield to me at a pedestrian crossing and almost ran me over while making a right turn. There are of course irresponsible bikers out there as well, but these are usually a small minority of young kids and they either quickly learn how to ride responsibly or become asphalt paint. The wast majority of us are very responsible as self preservation is our first priority. I can also say that ever since I started riding I also became a much more attentive and courteous driver as well.

I have friends that ride both Sport and Cruisers and they all tell me similar stories to what you just said.