Motorists hate cyclists for a number of reasons.

There are some cyclist that give cycling a bad name because they ARE *******s.
There are some that scare the crap out of motorists without trying to be *******s.
There are motorists that are scared of anything that could get in their way.
There are motorists that are jealous.
There are motorists that are just plain ignorant.

And then there are the rest of motorists that make up the majority that don't have an issue with cyclist, and go out of there way to look out for us.