Well, if you take the long view then the earth will be consumed by the expanding sun and the entire history of everything on it will be erased as if it never ex

Well, if you take the long view then the earth will be consumed by the expanding sun and the entire history of everything on it will be erased as if it never existed. So nothing any human has done or likely will do matters. Hitler is as insignificant as gandhi. But ... there are many lifetimes between now and then, and the quality of those lifetimes (at least the earliest ones) is something we can have an influence on, so what we do matters a lot. So, really, it boils down to what scale you choose to measure the consequences of your actions by.