The reason is very simple - profit.
The rabbits were not worth much to the Europeans, but were to the Aztecs, but the cocoa beans for the Europeans were like gold. They were a very attractive exotic product from which unique and unseen things were made. In the European market the cocoa beans had enormous price, and the demand for it was very high especially from the aristocracy which loved it and didn't speared money for it.
It turned into a riot after someone threw a bomb at police at least eight people died as a result of the violence that day.
Answer:
Gold and Farming. Opportunity.
The United States tried to stay uninvolved in most of the war until Pearl Harbor this is what led America into World War II
