same archetype with Fluder from Overlord,
they will do anything for their research even if it sold their soul to evil or become ghost.
For any kind of intellectual, being undead is a dream come true. Especially if you retain your intellect and memories, and gain magical powers in exchange. Who needs that fleshy body anyway?

So many downsides. Only upsides to becoming a Lich (which still has a corporeal form), Vampire (Corporeal, but craves blood and weakness to Light and other religious shenanigans, downside), or Specter/Phantom (Incorporeal, feels like a tossup if it's a downside or an upside to not be able to touch things/be touched).
'sides, evil or good is kind of a moot dichotonomy. Some people do evil to evil people, which could be considered a good thing, and some do good to good people, but it might be considered evil by some.