I would wager that most if not all downturns lead to greater concentration of wealth, since they invariably favor those that cover their risks with tail hedges

I would wager that most if not all downturns lead to greater concentration of wealth, since they invariably favor those that cover their risks with tail hedges and maintain a cash reserve for these market events. People who do this are far less common than those that don't and ownership will inevitably flow most dramatically to those that are prepared in a downtown. The converse, where everyone is prepared, at best would lead to maintaining the status quo, since everyone is ready and willing to pick up the few assets that are forced into a firesale if any.