As people get older, they tend to wonder if what their doing is valuable, or even morally right. So I think as Facebooks employees are getting older, they naturally want to leave. At this point Facebook is one big click bait site and that's not something people want to work on long term.
If Facebook was more about bringing people closer together, and less about showing ads down the throats of it's users, more people would want to work there.
Yet they have a lot of bright people working there and every year a ton of new-grads fight for the chance for an internship there. Plus the company is doing really well and treating their employees really well. A top 5 best places to work at according to Glassdoor. It really must be so miserable there...
EPA is shitty, but the FB campus is right on the bay and not in EPA. The only shitty thing about it is that you have to deal with the Dumbarton bridge traffic, which is good or bad depending on which side of the bay you live on.
