I asked my friends and family to download Signal.
They were resistant. It took a long time. But there are ample new opportunities appearing on a daily basis to show them why a cross platform privacy-focused messenger is a better idea than being trapped in a walled garden.
But eventually they understood. And because they care about me, they use Signal to communicate with me. For some of them I'm their only Signal contact. With others, they now have other friends from other circles who have similar concerns.
The more other people they hear mention Signal, the more likely they are to use it. Be the change you want to see.