I agree. As has been discussed on P&L recently, I think some of the factors behind this rage include:
1. Some people consider cyclists to be a challenge to their values: they see owning a car as an important statement of their success, they may feel they have worked hard to own a (in their view) nice car, they perceive themselves to be skilled drivers and wish to demonstrate that with manly acceleration and speed, and there we are on our (in their view) cheap, slow bicycles, basically telling them we don't give a f about what they think is important.
2. For others, seeing a cyclist is a challenge to the travel choices they have made: they have rationalised their decision to drive on the grounds that cycling is impractical, dangerous, slow, etc etc etc, and there we are, by our very existence, telling them they are wrong. People don't like being proved wrong.
3. And for a different group again, probably mostly the more risk-averse drivers, we are irresponsible, not just because we are taking risks for ourselves, but we are also imposing an additional burden on them to avoid hitting us. These are the sort of drivers who post comments on 'have your say' sites along the lines of "drivers already have too many other things to look out for without cyclists etc etc etc". Lots of drivers are nervous around cyclists, and don't really know how to overtake, especially when under pressure from following drivers. They aren't anti-cyclist per se, but think we should only be on off-road paths.
4. And cutting across all of these is a perception that there is a territorial struggle for road space as roads become more congested. This pits different groups against each other: instead of recognising that different modes are appropriate at different times and for different journeys (as most of us do here), lots of people become entrenched in a kind of motorist as victim mentality (egged on by the media), in which congestion has nothing to do with their own choices and can be blamed on others- cyclists, buses, lorries, the school run, traffic light phasing, traffic calming etc etc.
In all these cases, many people's attitudes will change through exposure to higher levels of cycling, but sadly the process of getting higher levels of cycling seems to provoke an even greater level of hostility than when we are simply an easily ignored tiny minority. And there will always be a hard-core who don't think we should be on the road at all.