Not buying that argument. Facebook just ran a Super Bowl ad, which cost over $10 million just for 60 seconds of airtime (plus who knows how much they paid for production and celebrities). That's part of user acquisition. And it certainly doesn't cost zero to attract advertisers (especially large corporate ones) who actually provide revenue.

In both cases, they are so ubiquitous that they aren't really after new users, just increased engagement/usage. And I'd bet Uber's per-user usage growth exceeds Facebook's right now.

It was also their first super bowl ad ever, so they grew to their size without needing big ads.

The message of that ad has nothing to do with introducing their product to the five remaining people on Earth who do not know about FB. The message of that ad is, "Hi we're Facebook, sorry about the whole election thing, oh and please do not regulate us."