You're comparing apples and oranges when you compare Uber with Facebook. A better comparison would be with Craigslist.
As a rule don’t complain about being downvoted - it just brings you more downvotes.
> Uber is a marketplace. Facebook is a social network. Craigslist is a marketplace. Uber's network effect works the same way Craigslist's does, and is not so much similar to Facebook's network effect.