Capitalism can only be justified with preconceived assumptions and not objective facts. Looking at the fundamentals of the system, one cannot rationalize that capitalism is beneficial, so the mind rationalizes that it is necessary.
For example, one simply cannot rationalize the existence of classes on the basis that they deserve what they have, or that the owning classes play any sort of role vital to the process of production. So instead, the human rationalizes the existence of classes on the flimsy basis that without them, without that position to strive for, without the final reward of completely removing yourself from productive work, productivity would plummet in all production.
You cannot rationalize that capitalism is good based on any evidence, because there is none. Instead it is rationalized by its supporters as a necessary evil. The dominant ideas of any epoch are the ideas of its ruling class.
This is the harder struggle to win—the struggle most people go through. That and blatent individualism. “Yeah, no one would be starving or homeless, but would everyone have the opportunity to direct their own films?”
Marx said that capitalism broke apart the feudal ties between families and bloodlines or “pitilessly torn asunder the motley feudal ties that bound man to his ‘natural superiors’”
but then “…left remaining no other nexus between man and man than naked self-interest, than callous ‘cash payment.’”