down·fall 
/ˈdaʊnˌfɑ:l/ noun
plural down·falls /ˈdaʊnˌfɑ:l/ noun [count] 1 : a sudden loss of power, happiness, success, etc.
▪ She was blamed for the company's downfall. [=decline, ruin] ▪ Their downfall was the result of several bad decisions. 2 : something that causes failure
▪ In the end, gambling proved to be his downfall. [=ruin, undoing] ▪ Bad decision-making was their downfall.
▪ She was blamed for the company's downfall. [=decline, ruin] ▪ Their downfall was the result of several bad decisions.
▪ In the end, gambling proved to be his downfall. [=ruin, undoing] ▪ Bad decision-making was their downfall.
