Fundamentally, it's very simple... To paraphrase Churchill (who paraphrased someone else): capitalism is the worst system, except for all those other systems that have been tried from time to time.
There's nothing perfect under the sun, because we humans are very imperfect beings. Capitalism is the best compromise we've currently been able to come up with. However, it's stupid to deny that capitalism has flaws. We can just try to make sure that we minimize the negative aspects and achieve the optimal cost/benefit tradeoff.