Both capital owners and workers are paid according to the prices set by the free market for their input. Most of the generated wealth however is captured by the society (ie we each derive more value from the stuff we buy than the cost we pay for it) and by the government - taxes on work, consumption and profit are usually much larger than other costs in a company operation.

Capital tends to concentrate, indeed - but that is also a good thing as it allows bigger enterprises. However the cost to build a new business has been steadily decreasing over the year together with the cost of capital while its availability has been increasing. Today's most productive people can easily open their own practices and set their price on their own contracts. The "rent" they pay is hugely outweighs by their future profits.

If you want to rail agains something, rail against the fact that financial education and investing is not more widespread so people do not understand that they can participate and invest in capital markets from very low amounts of money. Capitalism is powerful and empowering but requires work and education.