Oh come on, It is very well known that the Facebook bar to get hired is ruthless and very high, it requires studying for weeks to pass the leetcode interviews. They just decided to get the extra 20k$/year to be at Meta because this is what they wanted to optimize for.

I'm sure some of them might not have options but those are very clearly a smll minority working in niche fields. You don't get to Meta when you are a struggling engineer. You get there because you want to squeeze every single $ you can.