Comics

As with all things comics: it depends on the writer. Some writers do approach him as a genocidal mutant supremacist who sees humanity as inferior beings....but thats frankly boring and shallow. The more interesting take on magneto is that he's basically a pragmatic fatalist. His experiences in the Holocaust and the nature of mutation and evolutionary history have convinced him that coexistence simply isn't possible. Tragic though it may be, a genocidal war that ends with one survivor is unavoidable and inevitable.

To this point...he's had several solutions he's been open to. He's seen killing them all as the most likely outcome but he's also considered complete peaceful separation or even co-existsnce.