Here's my 2 cents:
Had Hitler avoided invading Russia and France, he could have remained in power for years .
Plus, it made no sense to me to execute so many Jews in the gas chambers.
He had no choice, Stalin was about to invade all of Europe (he had already invaded and made war on a few countries in the years before ww2) and Hitlers invasion was a preemptive strike to prevent the soviet tide sweeping away the european culture and bathing in in communism. Again, a war of ideologies. There is an xcellent reason germany was so successful initially and that is because they caught the russians in offensive rather than defensive positions. Mussolinis invasion of greece that year and hitler having to shore up that catastrophe cost him 5 weeks, and that delayed the invasion of the ussr by 5 weeks. Consider he was within sight of moscow when the first snows hit that winter- 5 extra weeks and a very different outcome could have been created. Pretty crazy huh?
And yes it makes zero sense from a tactical sense. Why waste valuable war resources on genocide when you are already losing? In 1944 when the hololcaust is alleged to have begun properly, germany was losing badly and the jews were the last of hit concern. If hitler was really intending to destroy their race hed have done so in the 1930s before the war. Above all else German war doctrine is efficient. Wasting time and resources on something not important to their war effort is not efficient.