Every bubble consists of a trend that can be observed in the real world and a misconception relating to that trend. The two elements interact with each other in a reflexive manner.

Find the trend whose premise is false, and bet against it.

Who most benefits from keeping marijuana illegal? The greatest beneficiaries are the major criminal organizations in Mexico and elsewhere that earn billions of dollars annually from this illicit trade - and who would rapidly lose their competitive advantage if marijuana were a legal commodity.

I am against market fundamentalism. I think this propaganda that government involvement is always bad has been very successful - but also very harmful to our society.

Regulating and taxing marijuana would simultaneously save taxpayers billions of dollars in enforcement and incarceration costs, while providing many billions of dollars in revenue annually.

I am not well qualified to criticize the theory of rational expectations and the efficient market hypothesis because as a market participant I considered them so unrealistic that I never bothered to study them.

There is very little difference between speculation and investment. The only difference is basically that investments are successful speculations because if you successfully anticipate the future you make a speculative profit.