What wrong did the Jews do???

Most of those who disappeared in the Nazi Holocaust were Jews, others were Jehovah's Witnesses, intellectuals and dissidents. The Vichy government did deport 25% of the Jewish population before the war; 75 000 of them perished in concentration camps. The others who were still in France, saw condemned by restrictive laws. The Jews were ordered to wear distinctive signs, access and public sector jobs they were banned. Jews were ill-treated all over the world.They were mass massacred in Germany and were ill treated in other countries.I still could not figure why Jews in particular are treated like this.What made Hitler think that "Jews where the reason behind the downfall of Germany in the First World War"?