I've been studying a bit on the Holocaust, and I came across a couple of interesting and seemingly contradictory points. I watched the film "The Rise and Fall of the Third Reich" and there's a bit that makes it seem as though concentration camps were operated for profits.

However, I'm also reading The Origins of Totalitarianism by Hannah Arendt and she states unequivocally that concentration camps were wasteful operations not motivated by profit:

"The concentration camp as an institution was not established for the sake of any possible labor yield; the only permanent economic function of the camps has been the financing of their own supervisory apparatus; thus from the economic point of view the concentration camps exist mostly for their own sake."

Was the profit a real thing? Was it a primary motivating factor in the methods of execution (gas and cremation)?

I know this is an enormously complex question but I would also be open to suggestions for further reading or viewing.