I don't like it when over weight people walk slow on the sidewalk while I walk my dog, does this mean I have the right to punch them and shove them off the side while screaming insults at them? Or better yet, does this mean that I have to label every single over weight person I see as an obstacle that must be harassed? Absolutely not to both of those questions.
I think most of the haters have encountered 1 or more cyclists that were doing something that they found annoying, so they labeled all cyclists as obstacles that need to be shown their place. I honestly think that some of them believe in their minds that ALL cyclists are wastes of oxygen and should be harassed at every possible moment.
Another assumption that many drivers make is "That's just a cyclist, they can't be doing more than 5 mph." 2 seconds later I'm hitting my breaks at 25 mph and swerving as they turn in front of me. They then feel embarrassed by their stupidity and reckless driving, but instead of admitting their fault, they choose to blame the cyclist and proceed to yell spineless insults.
Some people are just naturally intolerant, and there's not much you can do short of beating them with a bicycle pump. *Sarcasm* In seriousness, I try to ignore the guys that pass within a few inches or yell insults, but if they say something like "I'll kill you" or throw something, I record their tag number and call 911. Even if they're just having fun, they're not going to have it at my expense. Both of those things can be seen as assault or intent to kill, both of which will net them some jail time if they are caught.
But for the average a-hole, a simple smile + wave usually calms them down. They thought they were inconveniencing you, which they are, but if you act like they aren't they'll be less inclined to repeat the offense.
Just my 2 cents, time to leave for work.