I think it's mostly this mindset that keeps that being true. As soon as some of your friends defect from FB, it becomes much easier to defect yourself. Or, you could be the first person, and make it a bit more viable for your other friends to stop.

At this point, most of my friends don't really use Facebook much, we mostly stick to messaging apps and email. Maybe start by making a chat group in Telegram and telling people about it?