[Note: This post is prompted by nothing in particular. I just want to have it on hand so as to save me some typing when the next person cleverly diagnoses the hypocrisy of a Marxist who participates in capitalism.]
The Marxist critique of capitalism is that it is a totalizing system that forces everyone to participate in it. Hence it is not hypocritical for a Marxist to participate in that system while working toward a revolutionary change in the mode of production.
Just the opposite: it would be profoundly hypocritical for a Marxist to presume that they could individually “opt out” of capitalism or preserve themselves from complicity with the exploitation and destruction the capitalist system produces. That would mean buying into the capitalist illusion that everything is ultimately determined by individual choices.
Yes, it is possible to be more or less exploitative, more or less complicit with the very worst — but charging money for Marxist books, for instance, is not hypocritical. If you think it is, then you simply do not understand Marxist theory, full stop.