Yeah and that is I think the reason why actually villain quests fail so often. I have not in all the years I have been following Warhammer quests seen a single chaos quest make it to more than 20 pages and a handful of updates.
Same with villain campaigns in D&D—it either fades because everyone gets bored of the concept, or you end up fighting something worse and end up just being an excessively violent good guy. Being capital-E Evil just isn't narratively satisfying for most people, unless you can twist that into being "bad for the sake of the greater good" (see Worm and A Practical Guide), at which point you're no longer evil, you're just a flawed person trying to help people.