Nobody has to use these platforms, unless everyone else is using these platforms.
Have you ever been that one person who is being regularly invited to an event but you aren't in a Messenger or Whatsapp group to receive it? Pretty soon you stop receiving invitations. This is actually worse in the case of Whatsapp outside America, since it's used more often than it should for business, and if you don't make yourself accessible for business, you don't eat.
>If you want your messages encrypted, do it yourself.
I've been "that guy" trying to tell others about PGP. I still get jokes about acting like I'm hiding from the FBI occasionally, even in this age where privacy is mainstream enough where I can point them to a Joe Rogan podcast featuring Edward Snowden. People care, but it has to be frictionless.