As I see it, it's less about how much harm those specific things do, and more about how viable the alternatives are. I expect that all governments makes tax avoidance/evasion difficult, and I suspect that paying taxes to any government will support a military. The lifestyle changes involved in actually living sustainably (as opposed to being 'slightly better than the US average' or applying greenwash) seem pretty significant and possibly unattainable for most of us, as well. (I could be wrong on the latter in a general sense; I haven't looked into it, since I'm already relatively sure that it's beyond what I, personally, could manage.) Given that Warrigal was asking about the career move, though, I expect that he does have other viable options that could be pursued without completely turning his life upside down, and that's a significant difference between this decision and the other two.