They knew they would get this response, too. How could they not?
Israel can't ignore the hostages and rest on its laurels. There's no option to not respond when your citizens have been violently seized, held captive, tortured, maimed, raped. And Hamas knows their own defensive strategy relies heavily on using Palestinians as human shields, which will cause that inevitable response to be absolutely horrific. Hamas was relying on these horrors -- though I think perhaps the response has been a LOT sharper than any anticipated.
I think a lot of critics of the war, oddly, focus too much on what has happened after October 7th. When really we should be looking at what led up to it. And that's not to say that Hamas was justified because that level of depraved violence never is. But it IS to say that the Bibi administration was utterly complicit and that the fuse on this powder keg was lit long ago and no one with the power to do so seems to have made an effort to extinguish it. On October 6th, the whole world knew that the Bibi administration was made up of a corrupt, lunatic fringe of far-right religious fundamentalists bent on the total destruction of Palestine and a total takeover of Israel. On October 8th, the protests against Netanyahu for doing things like sending suitcases of money to Hamas or deleting the oversight of their Supreme Court were replaced with a completely different narrative.
I think both Hamas and Bibi's team thought they would politically benefit from this kind of violence. I think both are finding out they terribly misjudged things, though I am sure none will admit it. And the people -- mostly Palestinians, but also no doubt some Israelis -- are suffering terribly as a result of these two intractable right-wing theocratic organizations going about their religious war.