The Final Solution was based on Hitler's understanding of the nature of warfare (see below): If he didn't mind shedding the blood of his own (German) soldiers--why would he regret destroying millions of Jews? 

If he had no qualms about sending the "pick of the German people" into the hell of war--without regret for the "shedding of valuable German blood," then "naturally" he had the right to destroy million of men of an "inferior" race.

Hitler understood the Holocaust--and why he executed the project--better than most historians.

Nature if cruel. Therefore, we too may be cruel. If I don’t mind sending the pick of the German people into the hell of war without regret for the shedding of valuable German blood, then I have naturally the right to destroy millions of men of inferior races who increase like vermin. (Meltzer, 1976).