I don’t understand this narrative. If Hamas was as dismissive of the well being of the hostages as Israel is, there would have been no hostages left after a week.
Hamas wants to keep the hostages alive and reasonably well so they can use them to trade for the Palestinians being held hostage and (we know) are being tortured by Israel and hopefully stop the Israeli aggression atleast temporarily.
They wouldn’t have taken them just to ignore and/or kill them for no reason.