With as big as Facebook is, a lot of people (the majority?) are not directly connected to all the crap you see in the news. Sure, you can say they contribute to it, and you'd be totally correct...but Im sure what they see is a bunch of smart people working on cool technology with a good salary and free lunch.
So yeah, its probably "morally corrupt", no denying it, but so's the majority of companies that hire more than 50 people, one way or another. You have to work somewhere.
Then you have people who are trying to do the right thing from the inside. I knew someone who worked for Google purely to try and change its culture. The paycheck probably didn't hurt. There's a lot of these people.