I got my parents to install Signal a while ago, now in the recent 2-3 months their Signal contact lists have at least doubled when Signal got an unexpected boost by WhatsApp's privacy PR nightmare. I don't expect things to change much, though.

Because in the end normal users think about the functionality and price first, everything else second. Privacy? Just a neat-sounding bonus you can feel good about if your favorite app includes it and don't care about if it doesn't.