A key thing to point out is that the other Arab nations really have not helped the Palestinians that much, and a great deal of the conflict and imperilment of Israel was theirs, not the Palestinians.
They invaded Mandate Palestine in the middle of the Jewish-Palestinian post-independence fracas and took what are now the Palestinian territories for themselves. Every subsequent war was between the Arab nations and Israel, with the Palestinians mostly onlookers as they didn't have a state or army. The last war was in the early 70s, not counting subsequent Israeli attacks on its neighbours and ongoing occupation conflicts.