In L.Deighton's book: Blitzkrieg, he says that: "If there was one factor above all others that was to lead to Hitler's downfall, it was his absurd obsessive hatred of Jews. In the field of science alone, the persecution of the Jews deprived Hitler of military technology he would desperately need. A Nazi regime without anti-Semitism would have probably have had some form of atomic warhead and V-2 rockets to deliver them by the late 1930s. Thus I am of the opinion that but for his anti-Semitism Hitler night have conquered the world" How far would anyone agree with this? What was the drain on research and the economy by the anti-Semitism on the Nazi Reich?
On the scientific brain-drain: it was a real phenomenon. One of the first anti-Semitic laws passed by the Nazis ("Law for the Restoration of the Professional Civil Service") banned non-Aryans from teaching at universities (which were part of the civil service). This led to a fairly rapid emigration of Jewish scientists and professionals, many of whom went to the UK and, from there, the USA. These professors and scientists were some of the most enthusiastic participants in Allied defense science, and in a not insignificant number of cases were the instigators for major scientific projects (the atomic bomb being one of them). The German universities, which had been among the best in the world prior to the rise of the Nazis, were fairly gutted.
Did that cost Hitler the war? Well, this kind of counter-factual is a tricky thing, but the argument that they would have had an "atomic warhead" by the late 1930s is nonsense (nuclear fission was discovered — in Germany — only in late 1938, and turning the theory into a weapon takes time, even in the most optimistic of estimates). But would the Germans have been able to develop a nuclear weapon by the mid-1940s if they hadn't been anti-Semitic? Well, who knows. The most fanciful aspect, of course, is the idea that you can have someone like Hitler and the Nazis without the anti-Semitism. It was core to their ideology, world outlook, and politics. If you subtract the anti-Semitic aspects of the Nazis, you are not really talking about the Nazis anymore. You might as well imagine they could have invented unicorns, while they were at it.