You can't speculate and not lose money. The trick is to get out before you get blown up.
You know many restaurants with 800 million customers? You know many restaurants that have the capability to monetize their customers when they leave the restaurants?
You've made some decent points, but this isn't one of them.
Gotta adjust the customers to the ratio we are talking about, and then it might be close. The hotdog patent was intended to replace the potentiality of their database.
To be worth 100B, to me they would have to be able to make 5-10B a year with their current market position. (but with possible monetization) I have not mathed out whether that would be possible or what that would mean in terms of ad sales etc