(throwaway) I started at FB out of college relatively recently and wasn't there for very long, so I can't speak for longer-term/more senior employees but hopefully this is a bit helpful. I myself joined because I needed a job, the money was amazing, and I wanted to be in the Bay Area. When I went in, there were already questions about data privacy/elections, but this was still before Cambridge Analytica and the subsequent weekly bad news that's gone on for a year now. Personally I've never been a big FB user and wasn't that enthusiastic going in, but a) the money and b) the scale of their data/infrastructure/data infrastructure was attractive.

My impression was that many employees hold a self-contradictory view about the extent of their influence at the company. When asked about their jobs, they tell you that they're working hard on fixing the problem and making impact ("where better to fix it than from inside?"). But when confronted w/stories like Onavo, they get defensive because "it's a big company, I had no way of knowing." Which is fair, honestly; the problem is that they think they can fix anything in the first place. Part of the problem is that FB advertises itself internally as being super transparent but it isn't at all. (This applies mostly to product/data+ML people. The infra folks I worked with for the most part just want to make their money and go home.)

A lot of longtime employees joined when FB was good and amazing in the media, and it's hard for them to accept that it's really gone in a bad direction. A lot of younger ones join for the money, and/or because they're coming from FB's massive, culty college intern pipelines (especially if you come out of FBU) and confuse being dazzled by the perks with actually believing in the mission. The money is big for everyone (I was there for part of the long 2018 stretch where the stock price just fell and fell, and you could feel people getting antsy), and the defensiveness that comes from constantly seeing negative news is another part. Lots of blame thrown around internally (leakers, leadership, bad eng practices) but little responsibility; lots of sunk cost fallacy-ish thinking ("we all took jobs here for a reason, we can't just give up and leave").