Income distribution will **always** flow to the most productive members of an increasingly affluent society, away from those who contribute the least.That's how capitalism works. Money flows to those who are willing and able to best make money for others.
But that doesn't mean that the poor get "poorer", only that the poorer will steadily get further from the wealth levels of the richest.
Think of it as .1% annual **real** salary increases versus 4% real annual increases. Obviously both groups are getting better, but the difference between the two groups will keep growing.