Since everyone is posting their ideas, here is my scenario:
Putin planned the whole thing! Hamas fanatics are too stupid, Putin sold them a great plan, perhaps through some Iranian friends, and the Hamas idiots believed they will somehow kill Jews and survive. Now they know they will not survive, but it is too late.
What does Putin get out of this? Hamas sympathizers are outed in US, we have another mess, the public gets outraged with Biden who allowed all these Muslims to immigrate to the States, Trump becomes the President and sacrifices Ukraine. Hamas is terminated, but most Arabs do not like Hamas, so it is not really a problem for anyone if they are eliminated.
Edit: This also explains the hordes of English-speaking trolls that "support Hamas" on Twitter and other social media.