When the rich get too rich...

I remember vividly the scene in Pearl Buck's book The Good Earth. The desperate poor are struggling to survive in the city, where enormous wealth co-exists with starving multitudes. An elderly woman counsels the others, saying to wait. She has seen this before. When the rich get too rich, there will come a way. Soon thereafter happens the revolution and the uprising she had predicted.
The economic disparities we see in the US now are dangerous to stability and to democracy. The founding fathers well knew how hereditary ruling classes become corrupt and incompetent. Thomas Pain wrote his pamphlet  Agrarian Justice and proposed the inheritance tax as a way to compensate the working class for their labors, and to equalize the distribution of wealth.
This current situation threatens us all.