The original displaced Arabs not known as Palestinians back then were only about 400,000. Many of them were recent migrants from what are now OTHER countries such as Jordan. More recent than the Zionist pioneers. When "Palestinians" for example moved to Lebanon after Israel was created, Lebanon stuck them in camps, never integrating them. Was that Israel's fault that the Arab would used them as pawns?
As far as two million in Gaza, how many of those people NOW have keys to houses back in Israel? Come on man, normal people MOVE ON.