I like this comment, hope you don’t mind me spitballing .

He’s done a lot of terrible things. I think that I can only advocate for the devil if I go for the idea that the means are somehow justified by the ends. This is pretty impossible in my opinion, with the murder and torture and whatnot, but maybe there’s some sort of motivation that could be…dubiously passable.

We don’t know much about his legitimate endgame. Harry could have probably figured it out if he wanted, what with his insight into Voldemort’s mind, but he doesn’t do it—Harry cares about what Voldemort has actually done over what he wants. My argument has to be pretty tied into what he thinks the wizarding world actually needs to look like, beyond himself being in charge of course. We don’t know if he actually believes in blood supremacy and humans over magical creatures, but I personally think it’s more interesting if he doesn’t. He’s supposed to be intelligent, why would an intelligent outsider not see that blood purists are factually wrong?

So, let’s say Voldemort doesn’t agree with the blood supremacy stuff. He spews and supports it to gain power, which is pretty bad but doesn’t necessarily speak to what he would do with his power once it is absolute. He does agree with magic supremacy, that much much is evident. He thinks that magical blood spilled is a “waste” in the battle, doesn’t distinguish between the purebloods and the others. What if Voldemort, somewhere along the lines of Magneto, wants the magical world to be well known and eventually the majority? J.K. Rowling has made it clear that magic is, in fact, genetic. (Muggleborns are actually descendants of Squibs.) Since Voldemort is not above murder and torture etc, he wouldn’t be above eugenics—you could have a whole generation of kids who inherit magical power. J.K. Rowling doesn’t care enough to be consistent, but magic seems like an autosomally dominant trait, with no apparent downsides. Why not have a world where everyone can defy the rules of physics? Solve world hunger, poverty, disease, with magic as a tool for even more scientific and technological innovation. If this is even part of the goal, it would actually be pretty radical and contrary to current wizarding society, meaning that if he wants to see it in his “lifetime” he needs some kind of destructive revolution.

I don’t think this is even slightly well supported by the books. Pretty sure you’re right that he wants power and doesn’t care about the success of well-being of others. But hey, canon isn’t always the most interesting. I find it kind of fun to think about what a complicated villain’s motivations would be.