I've always assumed that the randomness of the markets was self-healing: if the markets exhibit non-randomness (and thus become predictable) some arbitrageur wi

I've always assumed that the randomness of the markets was self-healing: if the markets exhibit non-randomness (and thus become predictable) some arbitrageur will step in and correct it and then some trader will figure out a way to make money against the arbitrage. The best analogy I know of is Rock-Paper-Scissors. The commonly accepted optimal strategy is random, but against a random strategy always choosing rock works exactly as well. It is only if your opponent recognizes the lack of randomness and breaks their own randomness that they can capitalize, at which point you can counter.