Already there are claims that this cannot be an Israeli rocket (despite Hamas having nowhere near the capacity to commit damage like this), not necessarily because people may be blindly defending Israel but also perhaps because it's such an unimaginably heinous act, and because it appears so strategically self-harmful. But this attack can't be looked at in isolation, literally hours ago Israel bombed a UN school, it targeted truckloads of people travelling on the road it instructed people to take, it killed one of the most high profile journalists in the Arab world deliberately and muddied the waters of the investigation for *months*, their government and the IDF have not previously demonstrated good faith, they've repeatedly shown us their playbook, and on first impression the bombing of a hospital does not break from their playbook.
When a government and army's previous crimes are allowed to pass and it can weather every storm of criticism due to impenetrable and unconditional support of all variations of US governments, and when they're given an effective carte blanche to do whatever it takes to eliminate Hamas, this sort of thing can happen and in the eyes of those making the decision it can be calculated as rational.