Occupation of Palestine and existence of Israel are not the same thing. Most of the Zionists consider the occupation status of the West Bank and Gaza to be an unfortunate consequence of the conflict, and wish this occupation to end. The occupation is a consequence of the conflict, not it’s cause. To end the occupation, the conflict must be ended.
However, if you consider the mere existence of Israel an act of occupation, then it is another story. There are people, who deny the Jewish people the right for independence, for their own state in their national Homeland. And yet, they passionately advocate and even demand this right for other groups, including the Palestinian. A consider such people hypocrites, bigots, and anti-Semites. That’s what I think about people who oppose the existence of Israel (aka anti-Zionists).