What a surprise.
> this is the game that represents the economic reality
No, it isn't. Economic reality is nothing like flipping coins, neither for individuals, nor in the aggregate, except insofar as both contain a random element.
> it is still a markov process
So what? Saying "it's a Markov process" is simply making the observation that there is a random element. Yes, flipping coins has a random element, and yes, the market has a random element. It does not follow that flipping coins is a good model of the market. On this logic, coin-flipping would be a "good model" of any non-deterministic process.
The interesting thing about Markov processes is not that they contain random elements. The interesting thing about Markov processes is that you can make reliable predictions about some of them despite the fact that they contain random elements. But coin-flipping is not one of those processes about which interesting predictions can be made. The economy is.