Why did Hitler focus on the Jews?

Answer 1

Nazi Germany was not concerned only with Jews, although they certainly placed their greatest emphasis on killing Jews. They also attacked many other categories of people, including communists, gypsies, homosexuals, the mentally ill, and Jehovah's Witnesses. However, they chose to blame Jews for all the ills of Germany. Since there was a tradition of a thousand years of anti-Semitism in Europe, the German public was well prepared to blame all their problems on Jews, which they much preferred to the alternative of recognizing their own responsibility for their own problems.

Answer 2

Basically because of views that were propagated in Austria and Germany during his early youth, and he picked up on it.