As a software dev, if you're good enough to pass the screening at Facebook, you're good enough to have your pick of employers. You can go to one which is making a positive impact on the world.
HN software people love to call themselves Engineers with a capital E, but it seems all too often it gets forgotten that the practice of professional engineering requires adherence to professional codes of ethics.
Every accredited engineering program in the US and Canada requires that graduates have completed a Professional Ethics course, but of course the vast majority of "Software Engineers" aren't actually degree-holding engineers. They're by and large Comp Sci grads and to the best of my knowledge there isn't the same requirement for Ethics courses in computer science programs.
I don't think plumbers,electricians,lawyers, construction workers,car salespeople, you name it necessarily have inherently better average ethics (even once and if we define and agree on what those are or should be :)