An interesting point, and one that's certainly a liability of the system in some cases. Alternatively, many feel that a free market creates competition to provide lower priced goods, attract the best employees, rewards hard work instead of social background, and forces innovation and efficiency to remain competitive. Some also maintain it provides more choice to consumers (in order for ones goods/services to stand out from the crowd) and it rewards hard work instead of enforcing mediocrity (which can happen when even the minimum effort is guaranteed a reward). As has been noted, those who are stupid, lazy, or just horribly unlucky are often relagated to poverty and dissatisfaction.
To idrinor's point... Often times, those who to excel in areas that are less valued by a society, or areas that are over saturated with prospective workers, often do not receive what they feel to be fair compensation for their pursuits. Much as in nature, the underdog does not necessarily win and sometimes nice guys finish last. Intentionally gaining an increasing share in a shrinking market or mastering a skill set which people are unwilling to engage in trade for, is a poor choice unless someone feels the very act of pursuing that endeavor is reward enough. And in that case, where is the problem? Just my opinion, and I'm sure there are many others who would disagree.