If they don't want to use private communication then just leave it. If you want privacy you have to get used to having a less social life, at least online. That's the key really, if you want a social life, you have to start going offline, out into the real world and meet people. Get to know your neighborhood a bit or join some outdoor activity or club or something. I know it's weird at first about going outside because we're all basement computer nerds but you will find freedom without all the online surveillance when you leave your home.
JK, because next challenge is to convince everyone you meet that they should leave their phones are home and if you thought getting people to use Signal is hard you have no idea because that's just step 1.
deleting this