Sorry for the slow reply on this. There is probably something to what you are saying. However, in the case of the Holocaust we need to recognize the institutional framework that helps to keep “Holocaust awareness” (or whatever you want to call it) alive.
The state of Israel rests much of its claim to legitimacy on what happened during the Holocaust. Several well-endowed organizations like the Wiesenthal Center spend large sums of money keeping the Holocaust in the public eye. Tens of millions of evangelical Christians in the U.S. and elsewhere believe the Holocaust fulfilled Biblical prophecy and use it as a way to interpret today’s international landscape.
I can’t think of another event that aligns these sorts of interests that collectively control so much money. I don’t know if this is really an answer to your original question, but it seems to me like the attention given to the Holocaust is as much due to these factors as to the psychological ones you mention.