This isn't an uncommon sentiment in the context of historical loss of life. The reason for this is that we have no real connection to those who did die. I hate to quote Stalin but when "one man dies its a tragedy, when a million die its a statistic". We can learn about a person, or know them and through that we can empathize more readily with that man's death, but when you look at all of them together its so overwhelming, there is essentially a nameless, faceless crowd that ceased to exist long before we ever lived.
Its easier with distance to look at the events of world war 2 and feel disconnect, with time we are not spurred to an impassioned, emotional response and are more like a third, uninvolved party.
Of course I'm not advocating that loss of millions upon million wasn't tragic, and its def a bit different when coupling all of the resulting chaos. Something to think about.