[kunimu]

It is entirely possible to be a skeptic of capitalism, its application and its effects while engaging in a market in which capitalists provide goods and services. It is also possible to do so and sell your own labour-power (which is what workers do). To say that one's skepticism or criticism is invalid because of participation is equivalent to saying that the feudal serf may not complain about his position: after all, his pick and clothes were provided by his lord. He ought to be grateful!