It only takes one, or maybe two. Recently, we were riding on South Higuera on a SLO Bike Club ride. Even though the shoulder was in good condition and wide enough for two riders, we all rode on the shoulder.
A solo rider passed us, riding near the middle of the road. Several of us yelled at him that there was a car coming up behind him.
He ignored us until the car finally honked. Then he moved over some.
Just minutes later, another solo rider passed us, doing the same thing. We again tried to get him to move over. The car finally passed in the other lane. It slowed down and the passenger gave him a piece of his mind.
No one in our group recognized either of these riders. Neither of these guys had a mirror. Neither of them showed any common courtesy.
Both of them are the kind of rider that gives bicycle riders a bad name.
If you are someone or know someone who rides like this, owning the road because you think you have the right, remember that you are incredibly vulnerable. “You may be right. You may be dead right.”