But why are you ridiculing them ? Its their choice isnt it. ...do you walk around town ridiculing (what you perceive) to be a minority group.
Do you do it their face ?
I have had umpteen conversations with people, some on bikes, some not, in UK giving it the "why ain't you wearing a helmet?" routine.
I've spoken to several dozen Danes about why they wear a helmet, and all, bar one, have rolled their eyes and admitted they either do it to shut the significant other, who does not cycle, or children, up, or to persuade their kids to wear one. Come to think of it the one was a Swede from Malmo and he just told me to Feck Off.
Friends can take ridicule, the ability to laugh at yourself is a key skill.