As a drug it's actually pretty benign.
But every time I buy coffee, I am feeding the beast of global exploitation and environmental damage.
Compared to drinking coffee, the alternative is: simply don't do that. And if I take the alternative, the carbon footprint, other environmental footprint reduces a bit and reduces the profits of exploitative power structures.
The industry is just a waste of fossil fuels and logistics, really, seeing as it serves no particular purpose because life runs just fine without coffee.
Do whatever but if it's exploitation you're concerned about you could always buy coffee from the Zapatistas