I always think of it like this: if Google fell apart, the world as we know would change if. If twitter/facebook fell apart, my day to day life would not change in any way.
I have played the same mind game. Literally nothing would change for me if facebook/twitter/instagram/snapchat ceased to exist now. Whatsapp I use but with friends who I have other contact info, like a phone number...
Google on the other hand is immensely useful.
It still amazes me that there are so many billions of advertising dollars to prop up something as useless as facebook and their snowflake-innovator-genius engineers with over 100k salaries.
Then probably you haven't understood one of the biggest user needs - people don't want to "be bored". They constantly want some entertainment as stimulus.
Look at people around you (grocery checkout lines or bus stop or subway or Starbucks) - everyone is glued to their phone screens. And Facebook is the ultimate magnet to waste those 2-5 min wait times one has to endure every so often. Earlier, people would get bored waiting in line, or strike conversations with strangers or just muse over random thoughts. No more. All that attention has gone to their smartphones.
And advertisers are simply following those eyeballs. Since Facebook manages to capture so much attention of so many humans, they rake in billions.
It still amazes me that there are so many billions of advertising dollars to prop up something as useless as facebook and their snowflake-innovator-genius engineers with over 100k salaries.