There's also the allegation that a) Facebook greatly overcounted (on purpose) the impressions from autoplaying videos and b) their ads target more people in an area than physically exist

"Value" is a tough thing to translate. Market cap, and whatever. Considering the fact so many people express difficulty in deleting their accounts - it won't let you, or it gets reactivated later - I'm just going to state the quiet part out loud here; Facebook's valuation is mostly or entirely fraud