There is effectively zero barrier to switching social networks. "Friends" that could only be accessed through Facebook I realized long ago were people I didn't actually care to talk to.
This is not true for billions of people for whom Facebook is the web. Their businesses run on it, their family only communicate through it, and giving it up would mean disconnecting, essentially, from their entire world.
I don't believe this premise that these people only communicate on Facebook.
Sure some businesses are forced on to the platform to communicate with a subset of customers but it's extremely rare that they aren't on all the social platforms AND have their own website.
Family members that are on Facebook have phone numbers and are on other platforms. Maybe you can't spam them with links to every conspiracy website you come across or an endless stream of your kid without them becoming annoyed, but you absolutely can communicate with them. Facebook has only stayed relevant because of the natural lag in popular websites (older folks always get on late) and by buying platforms people have switched to in recent years likes WhatsApp and Instagram. But people do switch and people also are on multiple platforms
A monopoly on what? Spamming users with cat videos / baby videos and various other irrelevancies?
I haven't used Facebook for many years and I can contact family and friends just fine. Granted I use WhatsApp, which is owned by Facebook, but WhatsApp doesn't suffer from censorship (to my knowledge).
There is no monopoly, but an oligopoly. How comfortably would you avoid all 3 of Apple, Google, and Facebook?
These 3 are very similar in their values, operate under the same legislation. The latter is especially worrying for people not from the US, because foreigners' rights are completely unprotected.
Try Telegram. I use neither Facebook nor Whatsapp.
I don't know what Facebook is for, but I'm told that Telegram is a great replacement for Whatsapp and even people who both have Whatsapp seem to prefer Telegram between them.
One nuance being that while having access to an ISP is becoming more and more of a necessity to function in today's society, one can live a very happy life without Facebook :)