They do spread misinformation which can harm others around you. So an aunt can stop chemo and start drinking urine causing her to die, which will affect you.

Be careful with "I don't care because it doesn't affect me" because if society is harmed, we will all feel it in some form. Like vaccinations. If the percentage of vaccinated people go below a certain threshold, also vaccinated people are at risk of getting sick and die. And often piss drinkers do not vaccinate.

Drinking urine is just one effect of mass misinformation and poor education. If this becomes more popular, you can assume other harmful things are also becoming more popular, endangering the general public.