Hitler didn't have much of a choice, he had to attack Russia before Russia became powerful enough to launch an offensive strike of their own, which would have probably happened by 1943. That's why Stalin tried not to provoke Hitler until then, even when he suspected the Nazis would strike in 1941.
Gator is correct. Hitler’s launching of Barbarossa was more or less a pre-emptive strike, or as I like to say, a strategy of “hit back first.”
If Germany was going to fight the USSR, there was never going to be a better time than the summer of 1941. The Wehrmacht was at the peak of its power, and the Red Army was at its nadir, but recovering quickly. And Stalin did indeed intend to start extorting concessions out of Hitler, but no sooner than 1942 when he figured his forces would be more prepared for war.
Hitler’s problem was logistics; the USSR was simply too big to be defeated and occupied in one campaign season. The Germans needed to plan for at least a two-year campaign, with a winter operational pause.
They didn’t, and now we are going to see how that worked out.