Here’s some things I personally do to get people on. I’ve gotten my girlfriend and my family over, and I got a group of friends over to Keybase before the Zoom days.

Do NOT mention privacy/encryption to anyone who doesn’t care about that stuff. Focus on the genuine benefits beyond that: online chat (no iPhone/Android stuff), reactions/stickers/editing/replying, good UI/UX, can message from computer (or have multiple devices in general).