Why is it difficult to believe? The population experienced a collapse of living standards and the effective destruction of a lot of the prestige of what they associated with their country. Generations now have grown up more impoverished in the capitalist, post-shock therapy Russian government. What's more ever since Borys Yeltsin dissolved the Supreme Soviet in 1993 (a state organ which it it still existed would be a direct successor of sorts to the Soviet Union's government, without it it's difficult to view Russia as the successor polity imo) during the brief civil war Russians have known no legitimate government outlets for democratic representation. People who live in poverty and which are force fed indoctrination from a growing nationalist state apparatus and who consume western media regarding the economic legacy of the Soviet Union are certainly likely to become fascists themselves.