This is NOT a comment on Facebook or Snapchat or any other company I'm involved in -- You're sort of right. The other part that fills in the logic is "what is

This is NOT a comment on Facebook or Snapchat or any other company I'm involved in -- You're sort of right. The other part that fills in the logic is "what is the value of business X to acquirer Y" -- seen through the eyes of acquirer Y -- business X when it becomes part of Y. When Y buys X, X's opinion or the market's opinion of what X is worth is only one input. The more important input is usually what Y thinks X will be worth as part of Y. That is hard to understand from outside of Y. I am aware of deals where the purchase price was way more than X thought they were worth, but Y still got a bargain -- and every other permutation you can imagine. For this reason it's very hard to have an objective view of what X is worth in the abstract -- the takeout price in an acquisition depends on who is buying it at least as much as any other factor.