Only because your Aura regenerates.

[Don't give him that look!]

I could get away with consuming someone's magnetite instead, but I'd still have to inflict some kind of damage on them either way.

[And magnetite, while alluring on it's own, definitely pales in comparison to the thought of a soul. Eugh. Demon thoughts aren't really good, honestly.]

And I'd probably have to find more people to take it from in general. And more frequently.