Why? Were they afraid that staying in Poland would lead to investigations, arrests, trials, and convictions for collaborating with the Nazis?
Maybe it was because of events like Kielce, where 42 returning Polish Jews were murdered by Polish police, soliders and civilians? en.wikipedia.org/wiki/Kielce_pogrom
Or maybe it was because of experiences like that of Ben Helfgott, who was 9 when the Nazis arrived in Piotrkow. He was protected by his Polish boss, but eventually ended up in Buchenwald then another camp. When he was liberated and went home, he was beatne up and almost killed by Polish army officers. His is quoted saying this here: bbc.co.uk/news/world-europe-42920934.
327 documented cases of attacks, with 1000-2000 victims. Summary here with extensive source references: en.wikipedia.org/wiki/Anti-Jewish_violence_in_Poland,_1944%E2%80%931946
So maybe that's why many Jews didn't stay and "rebuild".
That does not deingrate the many, many heroic acts of protection of persecuted people, especially Jews, in Poland. I know of some personal examples, not documented, but conversations with people, showing how numerous they were. But that was not the case for everyone. There are dark episodes too, very dark. These also happened. It's not a question of blame, it's a question of honesty and maturity.