Quote Originally Posted by dismal

It's got to be better to make 10% than make 0% doing nothing with your money.
You're doing "nothing" in the short run. The point is you save it for the expensive upgrades (town hall levels, unit buildings) that you otherwise would need to wait to build.

Multiply expected delay (if you ahd built all those markets) by the expected cost of that delay (in conquest/pillaging/defense value), and you ahve an estimate of the opportunity cost of building markets.

I made some conserative assumptions about these costs and reached the conclusion that nothing > markets.

I also took it for granted that everyone builds higher level troop buildings. (which I think is a fair assumption -- who fights with peasants? or thinks it's optimal to fight with them?)