Polls show the large majority of Palestinians favor Hamas, which is why they elected it to rule Gaza. Do all residents favor Hamas? No. Neither did all Germans favor the Nazis. But in both cases, those who opposed the ruling group kept their mouths shut and had no power. So they had the same fate as the most rabid pro-Nazi and pro-Hamas residents.
When we and the Brits bombed Germany, the bombs fell on the anti-Nazis as well as the Nazis. If you allow a criminal gang to seize power, it becomes your problem. Is it fair? No, but that’s the way things work.