People do tell Jewish people who excuse inhumane behavior in Palestine by "but Holocaust!!" to get over it.

In contrast, Jewish people who are worried by antisemitism are generally not told to "get over the Holocaust".

The difference is in one case, past trauma is used to perpetuate current trauma; in the other, past trauma is used to avoid future trauma.

Also, your comparison of four years to "500 plus" is quite offensive, as if years count for more than what happened.