This is where it rises to society-level problem. If Facebook was a single-player game, leaving it would be as simple as getting a dog. But because most of the value you derive from Facebook comes from everyone else you know communicating with you through Facebook, the act of leaving becomes a big social sacrifice. This turns it from an individual issue to a collective action issue.

FWIW, I haven't been using Facebook much for the past couple of years. But - beyond unfollowing a bunch of pages and killing notificaitons - it didn't come from a conscious decisions. Over time, my feed became mostly ads and news articles, as Facebook tweaked their algos; meanwhile, most people I know retreated to other social networks. Too many to track at the same time. I also got more busy and focused on my immediate family. Some time ago I realized that I derive near-zero value from Facebook. My part of Fb's social graph pretty much dissolved on its own. I think this is going to be ultimately the fate of the entire graph.