What is your point? Their subsequent attempts to destroy the nascent Israeli state meant that they lost any right to their territory.
Going back into history, ancient Israel behaved very badly too (including attempts to destroy other nations) and were punished for it by losing their land. So according to your logic, their right to go back would also have been lost forever. Which makes your point moot.
No, the thing is the following - just prior to 1947/1948, Jews, Muslims and Christians mostly got along fine in what is supposed to be The HOLY Land. The people who lived there WANTED to live in The Holy Land, and had learnt, or were learning, how to get along with each other.
Then there was a sudden influx of people who hadn't wanted to live in The HOLY Land, and only went there because of what had happened to them in Europe. Now, according to Jews who already lived there, the new European Jews were a different sort for the most part. They were very aggressive, didn't want to make peace with their neighbours, murdered British soldiers, etc. And it was them who took charge of the new-born Jewish State. And ever since then, the same "all this land belongs to us, we have suffered so much, we deserve it all" mentality has prevailed among the leadership of Israel.
It is time now to listen to those conscientious Israelis whose voices are becoming louder, and warning their fellows of what is happening to them - that they are losing their soul. They are not traitors or "self-hating Jews". They are people with conscience. Israel will not be able to get away with the argument that no heed should be taken of the advice of those who aren't Jews or Israelis because "they just hate us", for much longer. Now there are plenty from within Israel saying the same. That the majority of Israelis seem to still be in favour of Israel's barbarous policies regarding Palestinians and their land, is without question. But popular belief in something doesn't make something right, and it all starts with a single "voice in the wilderness", which is then accompanied by others.