Picking on one of the least dangerous type of road users is weird.
I can only tell you my experience, but from where I'm from, I meet cyclists that know nothing about the rules 80% of the time. The people with cars at least know the rules most of the time, idiots doing dangerous shit is waaaay lower for them.
My rant about cyclists is endless, but the main things are
stop at the fucking red light, I saw way too much of this shit. It's not just for the cars, especially dangerous when cars are coming from the other direction.
even if you haven't stopped at the red light, you should fucking stop and let the other cars go (that come from the green light), but forget the lights, it's quite shitty already, that whenever I come across a cyclist, I no longer assume he knows who has the right of way (not familiar with the english terms).
make yourself visible! I have seen too many people on bikes at night without any vests or lights, some of them scared the shit out of me. I just don't understand those people, what's worse is if they have pretty expensive bikes (one of the guys I know is a bike nerd, and seeing what he rides and calls expensive, I think I can tell the difference between an expensive bike and a cheap one)
Don't be asshole to pedestrians while riding between them, it's the same on the roads, I hate people being assholes to others. Especially cars saying the cyclists slow them down, but then again I also saw lots of cyclists saying pedestrians slow them down
I also saw way too much cyclists thinking they can get away with shit, and tapping/hitting the roof/window of other cars.
And again, yes I see a lot of idiots in cars, some of them doing really dangerous stuff, but when looking at the percentage of people shitting on the rules, cyclists win by a landslide