I keep saying Markov process because it encodes any kind of chance over time on a large scale. It encodes how smart the entrepreneurs and investors are born, how many opportunities they get per time step, how corrupt the regulators are, how the competition will interfere. There are real averages in numerical terms for all of these parameters that can be used. A coin flip can represent an arbitrary model if you tweak the time lags and the payouts. And if the game is large enough you can fix the payouts and extend the lags until you hit your desired fixed payouts. Coin flipping on a large scale can capture almost any economic model.