The richest eight people now have the same wealth as the poorest 50 percent. Most of that wealth comes from investing (rather than labor). There is no probability model that would lead to this result; eventually someone on a "hot streak" is bound to lose.

What we're seeing is that luck may give some random people a boost at first, but that boost is sufficient to let them take all the winnings over time. The rich get richer. Investing success and wealth building follow a Darwinian rather than a probabilistic model.