That's cuz it's literally in our textbooks. In highschool my history teacher elected to do a unit on Israel. The textbooks skipped right over zionist militia terrorizing communities and creating the initial wave of refugees that eventually ended up on the Gaza strip.
The textbooks paint Israel as defending themselves when they militarily occupied Palestinian communities and the Arab states intervened. They made it seem like the Arab states attacked Israel for simply existing and not to stop literal fucking war crimes.
Than there's the Judeo-Christian element where some religious folk parrot "God's Chosen People!" and they give them carte blanche, taxpayer dollars, and unholy amounts of firepower.
...
Also AFAICT there's no common denominator as to who in the Jewish community denounces zionism or supports it. Maybe I'm just not intrenched enough to hear the consensus pushback that I'm sure exists on the tabernacle level; and I do refrain from demanding an answer from Jewish people cuz I think that's wrong. But its a 50/50 for who is willing to denounce zionism and who seems to have bought into the propaganda.