Note that you're excluding a middle that is perhaps worth considering. That is, the choice is not necessarily between "dealing with" a user account on an admin level (which generally amounts to forcing the user to change their ID and not much more), and spending hundreds of thousands of man-hours in counterproductive exchange.
A third option worth considering is not engaging in counterproductive exchanges, and focusing our attention elsewhere. (AKA, as you say, "don't feed the trolls".)
If it's worth saying, but not worth its own post, even in Discussion, it goes here.