It's not really about "like" or "not like" but fundamental economics and mathematics: things that grow behave differently then things that don't, and are worth more. Suppose FB found a way to consistently make 1B a year, give it to the investors, and only grow as much as inflation. Then the valuation would settle on something like 10-15 billion (plus however much cash it has on hand at that time). And a solid part of the market will love it as a long-term investment and tout its value. On the other hand, to value it at 50 billion you have to assume that its earnings will at least quintuple over time, so good luck to them.
