I don't know if you're being dense on purpose and shitting on the discussion or no, I'll be open minded.
- Israel's "right to exist" (we'll get to that in a minute) is not the only factor in what is seen as Zionism. It's the fact it has to exist as a religious ethnostate. Obviously lefties have a problem with that part more than its existence.
- The notion that a state has a "right" to exist is complete bullshit: nations don't exist in reality, it's a piece of land someone took with weapons, do you think Italy had a "right" to exist? People took arms and went to shoot other people (or better, we got the French to do it, but not important right now) and now it exists, that's literally all there is to it. All this talk of values and rules is pure fiction.
Israel exists now and there's almost 10 million folks in there so no, I wouldn't think it's right to go and deport them all away, but it doesn't exist because it had a "right" to exist, it does because they could occupy the land with little resistence, and in the post-holocaust landscape there were many people who wanted to go and start a new nation.
Let's not confuse the propaganda babble nations do with reality.