Why do people seem to always side with aggressive drivers?

I live in the northeastern US. Something I've noticed for quite some time is that most people seem to side with aggressive drivers over slow drivers. The incident that made me think of this happened last week. I was driving through town and was going the speed limit since I was very low on gas. There was another car behind me tailgating me obnoxiously. Eventually they illegally passed me in the left turning lane, cut me off, and proceeded to tailgate a minivan before cutting off more cars. Later that night I was hanging out with some friends and they said that I should've moved out of the way. When I asked what makes them more mad, someone weaving through traffic/cutting people off/tailgating or someone going slow in the left lane/otherwise going under the speed limit they said that the slow person makes them more mad. Other people I have since talked to said the slow person would make them more mad. I've seen a similar viewpoint from people online in the youtube comments on dashcam videos. Why is this?