Unfortunately the truth is, way too.many people use Facebook and Instagram way too much, and oftentimes you need to cast a wide net so you can reach people where they are.

It's a combination of ignorance and indifference. One of my social groups is around a sport, no necessity for knowledge around technology, and they will never ever leave Facebook. Those roots got laid down 15+ years ago and I would guess about 40% use FB as their sole social media, and another 50% use 1-2 other sites e.g. Instagram or Tiktok, types that are well known. The rest are aware of the existence of other sites and can explore more widely.