I used to be the standard kind of user of FB and Instagram who had friends and occasionally posted, etc. Then I realized it makes me feel like crap being on there and hated their business practices so stopped using it.
Lately though, I've had a few experiences that made me rethink how optional it really is. I recently sold a car and FB Marketplace has /so many more people/ along with a higher degree of trust than Craigslist. I got a bunch of offers from FB and none from Craigslist despite the same listing.
But even more significant is how businesses interact with the platforms. Because a bunch of people use FB/Insta, a lot of local businesses post new things or updates or specials there. Lately, new businesses are not even bothering with a website and just setting up an Insta. If I'm looking up what a store's hours were this past holiday weekend in the USA, then I know it's most likely going to be best to look it up on their Insta page. And just go ahead and see what the experience is to do that when you're not logged in!
Sure it'd be GREAT if those businesses didn't do that, but the alternatives aren't great and I'm not going to pressure them into reforming social media when they're just trying to make money off of selling an ice cream cone; they've got it hard enough!