I use all three apps, WhatsApp, Telegram and Signal, because others use them. And yes, none of my chats on telegram is encrypted because I'm mostly only in groups anyways.

What I've discovered is that especially groups show a certain inertness. For example, I observed that people from a certain context in one city all use signal but people from the same context in a neighboring city all use telegram. So all my groups from city A are in one messenger and groups from city B are in the other. This is weird, right? And these are really the same circles of people and I share many contacts between all groups. But I think it is just important what they started using and now they create more and more subsequent groups in the same messenger. None of them gives a reason to really switch to the other, so they don't.

Oh, and WhatsApp is only for the few people in my life that are quite unpolitical and uninformed, i.e. 'ordinary people'. Like people I meet at a language course or something work related etc.