Why did the USSR collapse?

A set of reasons led to the collapse of the country:
Ideological. After the struggle against the “personality cult”, the ideology caused more and more doubts among the population. The break with China, and Mao pointed out that Khrushchev’s course would lead to the collapse of socialism.
Economic. High military spending, dependence on oil exports, technology lag behind the leading countries.
Political. By the early 1980s, the old were in power, and then Gorbachev began a course of perestroika, which led to the “parade of sovereignties.”