All in all, this is mostly a question of policy (not in terms of typical market regulation through interest rates, money supply etc.) and not only market mechanisms.
Individuals with a high "wealth concentration" have a lot more power to pursue their goals ("gain [more] wealth [concentration], forgetting all but self"). Not only economic power, but -most importantly- power to enforce their interests politically.
Most western country (especially the US) policies of the last decades pretend to do something for citizens with a low "wealth concentration", but in the end just favor the rich.
Analyzing this trend only in economic terms and closing ones eyes (ears and mouth) regarding systematic political manipulation is hypocritical.