The people of other nations may not be used to making decisions themselves without a strong leader. They are used to being told what to do. So that is a reason why some governments may collapse. There is a dictatorship in Iraq ruled by Saddam Hussein. The United States should not be telling other nations what is right for them because there is no form of government that is right for everyone.
The Vietnam War started because Ngo Dinh Diem wanted to rule as a dictator over South Vietnam. People disagreed with him and wanted to overthrow him. He was ultimately assassinated. The United States government continued to support the South Vietnamese. Today, if America tried that kind of approach, people would disagree and possibly start another Vietnam war.
The United States should not tell other nations what to do. People in other nations have to be ready and willing to accept a democratic government because if they are not, many problems would result from the change.