[Jabanga]

The standard of living of the world's poor is improving faster than ever. I don't see cause to be concerned about a violent revolution.

As for the greater good justification: given income redistribution reduces how much wealth is generated, which you acknowledge, it goes to reason that over an infinite timescale, the society without income redistribution will become infinitely wealthier than the one with. A permanent boost to the exponent of economic growth leads, over a long enough time period, to a cumulatively larger gain for the welfare of the poor than any increase in redistribution could provide them, since the benefits of a permanent increase in the growth rate are recurring.