I think any product can become valuable depending on how you market it to your targeted users. FB is said to be somewhere you can go to be with friends and family; share memories, no matter where you are. If we’re going to ignore all of the ads and data mining going on behind the scenes, it’s easy to say that FB is doing a good for society. But it has its flaws.
Just earlier on HN there was a link about FB possibly selling user data. We have the Cambridge Analytica mess from the election.
Zuckerburg is smart when it comes to programming and tech, but running a company ethically is a different ballgame and that is the problem a lot of people have with his company. Nobody is saying he’s doing a bad job at building the product. He’s doing a bad job of managing the trust his users put into him when they use his service every single day.