Capitalism is the economic/political theory in which it is assumed that all men are selfish and look to achieve one's self interest rather than altruism assuming that if each individual wishes to do well, he or she will do as well as his or her ability will so allow (survival of the fittest).
There are extreme equity issues with capitalism, but it still remains the best economic system used to date using the modern standard. While true equality is only a dream in modern liberal democracy, the lowest class is still better off than the lowest class in other economic systems.
In the meantime, many live without the luxuries of the wealthy. However the fact that most can live in a middle class in relative comfort supports the benefit for the greatest amount of people. Realistically, somebody will always be proletariat (bottom feeder).
Capitalism is the economic system in which THE MAN screws everyone else.