People who think they have edge will invest, and so will some people who don't have a clue what they're doing. Some people will fit into both categories. I think that's true of investing generally.
you're unable to make an objective assessment of
the underlying value
Which would be a far more convincing argument if it wasn't the fashionable thing in the tech industry to try as hard as possible to never grow old and fat.
Just facts,
1) Creating a derivative market on Facebook employee options creates value for the Facebook employees because it means that they can now sell their options in a more liquid and better-priced market for cash (to potentially finance their kids education, help buy for a house or for hookers).
2) High frequency/automated trading tightens the bid-ask spread of stocks and does away with the "old boys" network of market-makers; making the purchase of stocks for both mutual funds/retail investors cheaper by $0.02/share-$0.05/share; at a volume of 4+ billion shares daily average volume. These cents add up to savings for market participants. But these machines could also turn around and manipulate the market and help save for hookers for traders/programmers who run them.
3) Weather derivatives, like other derivatives do have intrinsic values. For hedgers (such as hotels/ski slopes/airline industry/agriculture harvest that could be severely affected by inclement weather), they are insurance policies against risk that they are not willing to bear and help ensure that these businesses stay in business. However, if you have an army of Physics PhD who could model the risk/probability in weather derivatives; you could sell these insurance policies and make money to get hookers.
In "A Colossal Failure of Common Sense" there is a description of trading in distressed corporate bonds - I always wondered how you actually make money in bond markets and this was an interesting (to me) example of a scenario where what they were doing was obviously profitable and useful.