You could blame the global economy
There were a few events that caused the Revolutionary War. A few major ones include the Boston Tea Party, Britain's Intolerable Acts, The Continental Congress, The Battles of Lexington and Concord, and the Second Continental Congress.
If need be, I'll provide more information on each event specifically if you request it.
Yes i would agree with monroe doctrine with his statement in 1823
By 1500, the Spanish supplied almost half the gold in Europe, due almost entirely to their ruthless conquest of many different places in the New World, primarily in what is now Mexico and Central America.
The lives of the people in Nazi Germany and Khmer Rouge Cambodia were similar in some ways, but also different in many ways. In Germany, Hitler managed to create a cult figure from himself. He managed to make an economic boom in the country, opening lot of jobs, making the country a military super power, and improved the living conditions for the Germans. The ordinary German didn't had any troubles and actually had much better life than earlier. The problem was with the people that were opposing Hitler, or the ones he didn't liked, such as the people from other ethnic groups and political opponents, and he was solving that by putting them in concentration camps. Cambodia under the Khmer Rouge with Pohl Pot as leader was in terrible condition. The people of other ethnic groups were systemically killed. The Cambodians that didn't wanted to obey to the commands too got killed. The country was in terrible economic and social conditions, which made it one of the worst places for living on the planet.