I don't think this is a counterexample, and the imagination lacked wasn't in the scope of what can be done in policy work, but in the scope of what can be done

I don't think this is a counterexample, and the imagination lacked wasn't in the scope of what can be done in policy work, but in the scope of what can be done in tech. To stay with your examples, some of the Gate's foundation efforts have largely been tech efforts, some haven't. Some of the things I mentioned off-the-top have potential to reach 10s to 100s of millions of people. MFA is a big $ number partially because the US healthcare system is expensive and inefficient, so that draws focus on $ saved ... other efforts may focus on lives impacted at much lower $ impacts. Most public policy work isn't as big as MFA either. I'm not saying policy work isn't important or impactful. I'm rejecting the idea that you (generic 'you') can't have similar effect in technology to what you might be able to achieve in policy; especially the idea that this is so clearly true that the "right" thing to do is quit technology to go into policy. Even assuming you can be as effective in policy work as you are in tech work, which isn't a given.