Because their institutions are completely corrupt. There are no rules to the game so the powerful take everything. It is a smaller pie but if I can have it all, why do I care?
Prosperity correlates with powerful institutions (not necessarily democratic). But ultimately you need a set of rules that even the state has to follow.
It's ultimately a cultural issue. Russia never really experienced the liberalization and philosophical transformation of the enlightenment that occurred in Europe, they practiced monstrous feudalism until suddenly transitioning to socialism, which quickly became just as monstrous. Rules without ideology or philosophy are just things to be gamed - exactly as occurs often in those cultures without strong rule-of-law ideologies and societal game-theory countermeasures against corruption and malfeasance. Our politicians would rather twist the laws to make corruption legal than engage in illegal corruption because the drawbacks of illegality are so large. Russian politicians would rather do things extralegally because the system is facade and the real system is one of might makes right so the laws don't apply to them.
Prosperity correlates with powerful institutions (not necessarily democratic). But ultimately you need a set of rules that even the state has to follow.