When this contest started, my original optimistic estimate was that someone could accumulate a million gold in 5 seasons. I just finished my second season, and between my treasury and the sale value of orcs and equipment, my reachable gold amount is around 402,000 right now.
That sounds on-track to my estimate, but could be somewhat deceptive. Maybe 6 is a more accurate number of seasons. On the other hand, the value of games and orcs increases from here, so who knows?