I don't know how they can be worth that much, but I know shares are worth what the market is willing to pay. I could point to many examples of companies that have absolutely nothing but have a high market cap, and companies that have decent operations but nobody's interested in their stock and shares can be gotten at a fraction of their value.
If you need some specific examples, PM me and I will outline them.
DISCLAIMER: I am a dirty, rotten penny investor. I am not compensated by any stock. I've asked them to pay me, they refuse. I buy stock on the open market. I sell it there. I like money. I am greedy. I am under the care of a psychiatrist.