Capitalism provides many with the opportunity to display initiative. While the rigidity of a status society enjoins on everybody the unvarying performance of routine and does not tolerate any deviation from traditional patterns of conduct, capitalism encourages the innovator. Profit is the prize of successful deviation from customary types of procedure; loss is the penalty of those who sluggishly cling to obsolete methods. The individual is free to show what he can do in a better way than other people.
-Ludwig von Mises (The Anti-Capitalistic Mentality)
Socialism has no such incentive system in place – in fact, it is frowned upon. The only incentive is to climb upward through the Power structure. In doing so, they benefit only themselves.
Capitalism makes things better for everyone – even the poor.
(H/T: Cafe Hayek)