Liberals tend to say that the system just needs a few tweaks here and there while the reality is that the entire thing is rotten to the core and the stuff they enjoy now in their "developed" countries was built upon centuries of exploitation of other people, which is still ongoing stronger than ever.
When confronted with these facts, some liberals act defensively and instead of learning and growing in their understanding, they start aligning with right wing thinking. That's why the saying goes "scratch a liberal and a fascist bleeds".
My argument would be that individual actions are useless or even harmful. Collective, smart action is required. This problem is bigger than any one of us but not bigger than every one of us.