From talking with them there are two, correlated, factors. The most superficial one is that they suffer from extreme geopolitical Manichaeism, in that they view the US as absolutely evil and everyone that has an adversarial relationship with the US as good. The other is that they have Russia inherited the Soviet intelligent apparatus, and this includes the people that built long term relationships with communist party members and supporters, and this allows Russia to manipulate them easily, since they refuse to accept comrade Alexey who pretends to be their friend is actually agent Ivan from the FSB and doesn’t give a fuck about them.