Earlier quoted context omitted.
50 years ago people who smoked didn't care about the adverse effects mainly because they didn't know the dangers. As people who know the dangers of poor privacy choices we should protect those who have not had the opportunity to consider it yet.
Smoking will kill you. Liking funny cat videos on Facebook won't. I think you are comparing oranges and apples here.
Social media creates a semi-public record for bad actors to identify targets to persecute for whatever they've decided to retroactively declare to be a crime. That may be a small risk in a stable democracy, but it's still worth considering due to the magnitude of the potential consequences.