Income is proportionate to wealth, for the wealthy.
Income increases wealth, so the income of the wealthy grows.
Wages, meantime, are flat.
The percentage of income going to the wealthy, now vastly increased, will continue increasing.
Here's a simple table, that assumes wealth grows at a net rate of 10% a year:
Wealth % = wealthy income / total income (worker + wealthy)
This is just a figure demonstration, to illustrate the basic process at work.