Not that I have many facts to back this up economically, but I think at some point the top percentile have invested interest in either paying the bottom percentiles more or making it easier for them. Everyone at the top 10% somehow relies on the other 90% to consume something they create. Look at what Henry Ford did to pay his workers more, in the hopes they would buy their own Model T.
Buy I'm an optimist, so add salt to taste.