That's patently false. The conflict started with the rise of Zionism in the early 20th century fuelled by anti-semitism; wanting Jewish people out of Europe. This led to the Balfour deceleration in 1917, which caused an uprising in Palestine with people demanding an independent homeland. The British crushed this uprising. Then the UN backed a plan in 1947 to give Palestine to Jewish settlers which caused the 1948 war which led to mass expulsion of Palestinians from their homeland (whom have not been allowed to return since) and the creation of the Gaza ghetto. Every year, more land is taken in what has been called a "Salami" invasion (i.e. one small slice at a time) in Gaza and the West Bank, forcing people into worse and worse conditions in the world's largest open-air prison.

Furthermore, Hamas was not elected. There haven't been elections in Gaza since 2006. The median age in the strip is 18, meaning most of its population wasn't even born when Hamas took power. It is simply the largest gang in the prison.

This is the latest chapter in an incredibly sad story, not the start of it. In fact, just before the Hamas attack, Israel opened fire on unarmed protestors at the boarder. Literally a week before the attack.