'People' is a poorly defined notion here, and cannot be really used for any sane conclusions. Users have different practical, and security needs, therefore different priorities which define their behavior. PGP (and its alternatives) is to Whatsapp (and its alternatives) as apples to oranges.

Okay, the vast majority of the general population, the billions of people using apps like Whatsapp.

Note that the comment I replied to started from the rather categorical "nobody".