Indeed. Capitalism built the Pyramids and the Parthenon; capitalism took us to the Moon; capitalism made Homer write the Iliad for the license fees and produced the most widely printed book of all time, the Bible.
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More seriously, the lesson we should apply from Monopoly is that once the money is in few enough hands the "game" of capitalism is over.
Maybe we shouldn't consider Monopoly a game of 'capitalism'.
Although, it probably in some respects does represent the popular idea of capitalism and the reality of our current regulated economic system.
The game monopoly better represents a non free market economy. The players are constrained within the limited confines of the game. As players accrue money and resources they can't invest that into new businesses. The is no representation in the game of other economic pressures of supply and demand of human resources. All these limits are more analogous to a heavily regulated economy. And of course, part of the game is based simply on chance. Players aren't complete free to engage in free trade as they would see fit.
There are no limits in a real world economy on agreements, contracts etc between actors. Monopoly is a very closed system and in no way represents a real free economy.
I think you're confused about the definition of a monopoly. Most monopolies or cartels rise organically but then achieve such a dominant position that it becomes impossible for upstarts to challenge them.
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More seriously, the lesson we should apply from Monopoly is that once the money is in few enough hands the "game" of capitalism is over.