Several people around Hitler most notably Martin Bormann, convinced him to let them record his ramblings for posterity. These recordings were called Hitler’s Table Talk. They are absolutely fascinating.
I became Chancellor of the Reich at 43 and I’m only 52 today. With age optimism gets weaker… the spring relaxes. When I suffered my beer hall putsch and subsequent imprisonment in Landsburg that was back in 1923….I had only one idea to get back into the saddle. Today I no longer would be capable of the effort that implies. The awareness that one is no longer capable of that has something demoralizing about.
This is perhaps why Hitler was so obsessed with invading Russia. He worried that he would live to see the future he was creating. He feared that he would be a necessary ingredient
Let us hope that our Ministry for Eastern Territories will not, in conjunction with the Ministry of the Interior, introduce here our laws against contraception. There are plenty of other things with which our busybody officials can occupy their time; and thank God I shall not live to see them at it. If I did, I might regret ever having captured the country!
And here we see more evidence that Hitler was convinced his death would come sooner than he otherwise would prefer. Hitler was so aggravated that the British would not surrender, and that he had not eliminated them during the Battle of Britain, and that Britain actually drove them out of North Africa. He gambled that if he defeated Russia, Britain would fold. After all he felt in his heart that Britain was an Aryan nation and they should be kindred spirits.
In his delusional conspiracy theory matrix regarding the Jews, Hitler saw Jews as the creators of Communism, the worst of all political systems to him. And then they were Jews. He saw the invasion of the Soviet Union as a way to eliminate Communism and the remainders of the Jewish people. He abandoned North Africa because he thought he could accomplish another great Nazi goal: capture of the oil fields in the Caucasus, and fuel the Nazi war machine. He only gave Erwin Rommel four divisions for Afrika Korps. If he had devoted the attention to North Africa that he gave to Russia, he could have made the Mediterranean a German lake.
There will never be enough answers as to why he invaded Russia. This could be a few reasons why.