IME something like Signal is an easy sell since it's simple and works well. For all the fair criticism about relying on phone numbers it makes the onboarding easy. For other things compartmentalising helps, e.g., "okay we'll collaborate using this cloud file storage but I personally will be accessing it through the browser while keeping most of my files in a SyncThing over here". While I self-host certain things I don't volunteer to do that for family/friends because it will be too frustrating for everyone if/when I let them down.

In this kind of situation there's a fine line between someone who maximises their privacy through tech decisions and someone who makes their "correct" tech choices their self identity. If you drift into the latter, being asked to compromise can feel like an attack, leading to overreacting and coming across as insecure and annoying. Not to psychoanalyse anyone in particular but sometimes I think people need a reminder.