The weirdest thing about the zero-sum rhetoric to me is: when one person is demanding to benefit at the expense of someone else, if I'm neither of them, why am I supposed to care?
Suppose I'm not an American--like plenty of HN commenters--or alternatively that (as in reality) I am an American but I have good reasons to think that the personal benefit I derive from the presence of immigrants is greater than the cost to me as an individual, even were I to concede more generic economic arguments about wage competition. Then... why am I supposed to prioritize the interests of American tech workers over foreign immigrants?
I don't in general endorse an "I got mine, screw you" approach, nor one that says "hey GDP is going up so screw the losers", but if someone else is taking exactly that attitude just with a nationalistic inflection, it's hard to extend them a lot of empathy.