The success of the new nation was not a chance occurrence. Many aspects of the American Democracy stem directly from George Washington's decisions. These decisions he determined upon his own. Most nations never succeed after their revolutions. Revolutions turning on themselves and leading to more tyranny are far more common in history.
Human frailties lead to yet more tyranny and chaos.
This would have happened in the late 1700s but for one man - George Washington. He was in the right place at the right time.