The best and the brightest are always the first to read the writing on the wall and are always the first to flee. From Jeff Thomas at internationalman.com:
In 1933, Albert Einstein renounced his German citizenship soon after Adolf Hitler became Chancellor. Although that left him without a legal home, he was welcomed in England and later, the US, and eventually became a US citizen in 1935.
This was quite a risky move at the time, as he had no certainty of a better life outside of Germany, or even a prospective job. But he saw the writing on the wall. As a man of reason, he focused not on the present condition in Germany, but where events would ultimately lead. His focus was on the Germany of the future and he made a difficult call that those with less vision might not have made.
In 1940, Ludwig von Mises was perhaps the most gifted economist in Austria, as well as being a visionary of libertarian thinking. But he left Austria in that year. The Nazi expansion was already under way and he understood that, if anything, he was leaving late in the game, but before it became impossible to leave. On that day, Austria lost one of its best minds.