We have to do it. Some of us have to do it in different ways. Doing small things where you can is all well and good but literally none of us are making a single impact in capitalism by making different choices about how we're forced to participate in it. Focus on tearing it down together rather than picking apart individual choices because those individual choices still result in participating in capitalism.
I did some work with a christian non-profit a while back, and one of the few excellent nuggets of thought I got there was that everyone has a different "calling." Spirituality aside, the idea was that its ridiculous to be mad at someone because they're focusing on say, feeding the homeless, rather than ending domestic violence.
Both of these things are good. One person can not possibly devote all of their time to every cause, and being frustrated with someone over what you perceive as their laziness or uncaring attitude is ridiculous because more often than not they're doing what they can.
Your average leftist doesn't need to be told how cruel the conditions are in meat-packing facilities. Hell, I worked in one while I was working at that non-profit. We're on the same side, but life is hard, and food is expensive and sometimes I just need to grab a quick, shitty, disgusting burger on the way to work because I can't afford to be late again or I'll get fired.