Why the hate?

Recently there has been a drastic increase in the amount of road rage toward bikers. In the last week or so I have been honked at, yelled at, swerved at, revved at, nearly been hit by passing cars, nearly backed into, and been given the finger multiple times each.
What I don't understand is why riding a bike pisses a motorist off so much. Honestly, he or she will maybe, just maybe slow down. Most likely all he or she must do is nudge the steering wheel just a little in order to swing wide and not come dangerously close to hitting me. Maybe the motorist will be up to 20 seconds later to getting to where they are going, but surely no more. If 20 seconds matter that much he or she should have left earlier. Endangering the life of a cyclist is not worth it.
Again I ask myself why there is so much hate towards cyclists. Yesterday coming up to the lift bridge a guy in a very large pickup floored it from a 100 meters or so back as to get right up next to me. He then proceeded to yell about a sign that reads "walk bikes across bridge," then continued on to say something about how I am the cause of all the problems. I don't walk my bike across the bridge because the speed limit on it is 15 mph and it is all of 50 meters long, thus holding 15 is not a problem at all. Anyways back to this big truck, after him yelling at me he very intentionally swerved to the right (I was on the inside) trying to force me into the large metal guard rails on the road side. A quick pull of the brakes was barely enough to get me out of the way. All of this mind you is happening going over the lift bridge which has a grated metal surface, cars behind and in the other lane all at around 20 mph. Needless to say as soon as I was off the bridge I whipped out the old cell phone and gave 911 a ring. I had a nice chat with the helpful lady as she watched this dumbass drive through Canal Park (the slowest moving busiest traffic area in Duluth) with the traffic light cameras. Hopefully the cameras on the bridge caught the guy in action.
But back to my question, why do they hate us so much? Is it because we cyclists are out using our bodies in the beautiful summer sun, enjoying our ride for training or commuting. While the angry motorists are sitting in a hot car contributing to global warming and the American obesity problem? Or is there some other reason. I mean sure I might not stop fully at a stop sign or go the second before the light turns green. But I very often see a motorist doing the same thing, but he or she will be traveling much faster in something that can't stop on a dime.
All I really have to say is that motorists better get used to cyclists, because our numbers will start multiplying as the price of gas goes up.