Consumption of certain products is likely to have direct harmful consequences. For example, eating meat will, in expectation, increase the number of animals in factory farms. In addition, consuming some of these products may support harmful social norms. For example, eating meat can support the view that the interests of other species should be discounted or ignored. Moreover, the issues are not purely consequentialist, and there are deontological constraints on consumption choices (for instance, it might be unacceptable to buy from sweatshops even if refusing to do so did not create tangibly better outcomes).
There are, however, reasons to think that changing one’s own consumption decisions is not a cost-effective way to spend one’s time or money. One such factor is opportunity cost: spending more resources on ethically sourced products leaves fewer resources to spend on even more important projects. In addition, in many cases one person buying less of something can indirectly lead to others buying more, offsetting some or all the good done.
Aside from considering how we spend our consumption budget, another question is how much to spend on personal consumption, when that money could be instead used to fund good causes. Most members of the community budget reasonable portions of their income for themselves, to stay motivated, prevent burnout, and increase productivity (Kaufman, 2013).
Kaufman, Jeff. 2013. Keeping choices donation neutral.