No matter what, one thing you can say about Lenin and the Old Bolsheviks is that they passionately believed in their cause. Of course, Lenin and the others were mass-murdering maniacs, and their utopian delusions were completely contrary to reality, but a distinguishing factor of, say, Leon Trotsky’s work is that what he wrote was what he believed, and what he did–including his murders–reflected that.
By the time Leonid Brezhnev became Premier, the USSR was little more than a rotting husk of an empire mouldering upon a core of lies. It is hard to say whether anyone much believed in Communism, the USSR, the World Proletariat, or any of that by 1977. What the average apparatchik did believe was that lying was the best way to get by. So everyone just lied. The men at the top lied to keep their jobs. The military commanders lied about their armaments to keep Americans fearing Soviet strength. The common man lied about his happiness to keep his family safe. The apparatchiks lied to keep the people subservient. The industrial planners lied about production numbers to stay out of Siberia. You lied, lied, and lied some more, hoping that it would get better, or that at least you’d be able to lie your way to a comfortable retirement, perhaps near the Black Sea.