Based on my past conversations about this topic and the kind of people who say that.
“Israel should not exist” begs the following questions.
Who rules the area now? What form of government will be established? Which of the ethnic groups (that hate each other) are going to form that government? What happens to people deemed ‘colonizers’ and other minorities living there?
Who did you have such conversations with? People who hate Israel because they colonised Palestinian territory, or actual anti-semites? In the latter case, I can see how you would come to that conclusion, but in my experience, most people (at least on Lemmy) are part of the first group, who have no intention to kill everyone in Israel.
Regarding the questions, this is something both the Israelis and (more importantly) the Palestinians need to talk about to find the best solution for everyone involved. But they can all be answered without “Kill all the people living in Israel”.