That the rich get richer is just math. It's not a value statement.
Without active wealth redistribution, accelerating inequity is inevitable.
I personally don't care how we do it. UBI, cashectomies of windfall profits, restoring progressive taxation to subsidize the safety net. Whatever.
I am tired, however, of the bickering over the details. As though the primary issue at hand is tax brackets and capital gains. These food fights just muddy the core conundrum.
The trick is balancing capitalism with democracy, lifting the floor without lowering the ceiling.
 Kevin Phillips, Reagan's conservative economist, detailed our history of purposefully creating a middle class and the upper class' efforts to thwart such efforts:
Wealth and Democracy: A Political History of the American Rich Paperback 
Having watched Mark Blyth, he has a theory that the capitalistic system can operate in one of two modes (https://vimeo.com/247596824):
A) Mode that favors the workers (US before 1970)
B) Mode that favors the capitalists (US after Reagan & Thatcher)
When capitalism is in Mode A), you get horrible level of inflation, but rising wages and profits for the workers (and since one man's wage is another man's expense the prices rise too). It creates great environment for taking credits, since inflation devours any profit bank can make on a credit. This hurts the returns of capitalist and investors, who stage a "market-friendly revolution" that will change system to B).
When capitalism is in Mode B) you get stagnating wages, and rising profits for capitalists. On the other hand, this causes inequality. Credits are available, but generally a bad idea, since the wages are decreasing. Usually in this environment the Supply Chain is Globalized making it really hard for Labor to move, but making it super easy for Capital to transfer (as Mark says "Good luck striking, if I can move my production to China")
2. The unions that pushed wages up 1950-1970 also eroded America's manufacturing competitiveness and efficiency, which contributed to the outsourcing of manufacturing. The reason union membership numbers in the private sector declined was because the industries that employed unions contracted. And that was largely the doing of unions and the very generous collective bargaining agreements they got for themselves. IOW the gains they brought about were not sustainable. In contrast, the wage gains attained in the pre-union, free market era of the late 19th century were sustainable. They accompanied an increase in the competitiveness of American manufacturing, instead of coming at its expense.
Plenty of people would be fine with lowering the ceiling when the ceiling is currently "having a higher net worth than some nations". We don't need Bezos to be as rich as he is in order to motivate people to try hard. We don't need one unelected man wielding that level of power individually.