I agree that it's easy to discuss rationally from the outside.
Hamas is not a threat to Israeli existence. Without extensive and far superior outside help, Hamas could not hold a square meter of Israeli (non-Gazan) territory).
Do you have insight into why Israelis talk about an "existential" war? I'm not dismissing their feelings - WTF do I know? - but I think it goes beyond expected overreaction and the exaggerations of a few fringe figures.
(And obviously, existential or not, Israelis will not want to experience future attacks like this Oct 7.)