Answer:
There were many reasons, see explanation
Explanation:
Hitler tried to hide the existence of concentration camps for as long as possible. He made them far away from cities so people would be less likely to find them, therefore people did not really know about concentration camps until after the allied powers liberated the camps. Therefore, Jewish people did not know how bad things were.
Hitler had plans to invade the entirety of Europe, therefore Jewish people would have to move a different part of the world which is insanely expensive to do, and the risk of becoming homeless when suddenly moving somewhere so quickly is incredibly high.
As with immigrating to any country to live there, you have to apply for a visa, and cannot simply just go to that country since that would be illegal. Many countries were not willing to accept Jewish refugees, and escaping to the few that would is incredibly hard work. Since the entire government of many European countries got controlled by the Nazi party, Jewish people couldn't just simply go on an airplane to a different country. They would have to be smuggled into countries by boats illegally.
