Email, docs, music, maps etc have reasonable alternatives and you don’t depend on others to switch (a gmail user will receive my email from tuta). But with WhatsApp either you conceal and use it or you just don’t talk to people (tried convincing them to switch to signal and it simply doesn’t happen)
How do you deal with it?
Naomi Brockwell TV on YT or Odyssey had a video about that, forgot the name. You basically make it more painful to communicate on other platforms, reward for using your preferred platform (e.g. offer tickets to a game through preferred platform).
Don’t expect people to move completely, including close friends