I think people overthink spending money on things they don’t support. I think stealing it is justified, but If you’re doing academic studies or learning how to deprogram people, go ahead and buy a Nazi’s book if you have to.

That said, if you’re looking to argue with Holocaust deniers, trying to defeat them by studying their arguments is a classic blunder.

Conspiratorial thinking is rooted in social maladies, and attachment to a theory is a downstream effect. You can no more talk a Holocaust denier out of their belief with evidence than you can fix a broken watermain by sand bagging the street. If you’re trying to deprogram someone, you’ve actually got to learn how to get them to open up about the background experiences that led them to look for these answers and then find ways to help them find alternative hobbies that obviate their need for the conspiracy.

It’s a much slower process, but if that’s what you want to do, read up on that and don’t bother wasting money on Irving’s book.