D&D 5E A Lich with a Clone?

[Dausuul]

I don't know if sane and live forever can coexist. The mind eventually breaks down under the weight of memories and you begin to care as much about those short-lived Humans as much as you care about your pet goldfish, fun but disposable and it doesn't really matter if they die today, they didn't have that much life ahead of them anyway. It is part of why dragons can be so slow to act, 10, 20, even 50 years to them feels as long a wait as a week or so to you.

I'm also suspicious of elves, but at least most of them choose to die after a few centuries, if only to alleviate the boredom.

Well, "sane" is relative here. A wizard who's been using clone to stay alive for a thousand years is certainly going to have a different perspective, and probably a bundle of neuroses from seeing the deaths of endless friends and loved ones, plus a thousand years of cumulative culture shock.

But contrast that to the wizard who's spent a thousand years without even having friends or loved ones, who never sleeps or eats or drinks, who devours mortal souls to preserve that sleepless dark existence inside an animated corpse.

And then consider the mental state that would lead somebody to pick Door #2 in the first place.

No matter how wonky and weird Wizard McClone may be, she's a paragon of sanity next to Necromancer von Lich.