I believe it was installed, at least in part, by Israel. From The Intercept.

But did you also know that Hamas — which is an Arabic acronym for “Islamic Resistance Movement” — would probably not exist today were it not for the Jewish state? That the Israelis helped turn a bunch of fringe Palestinian Islamists in the late 1970s into one of the world’s most notorious militant groups? That Hamas is blowback?

This isn’t a conspiracy theory. Listen to former Israeli officials such as Brig. Gen. Yitzhak Segev, who was the Israeli military governor in Gaza in the early 1980s. Segev later told a New York Times reporter that he had helped finance the Palestinian Islamist movement as a “counterweight” to the secularists and leftists of the Palestine Liberation Organization and the Fatah party, led by Yasser Arafat (who himself referred to Hamas as “a creature of Israel.”)