Meh… Israel helped make Hamas big, way before they were known as Hamas. Back then they just were an offshoot of the egyptian Muslim Brotherhood organisation. Fatah was/is secular and Israel sought to utilize islamist organizations agaibst Fatah, who they saw as their main opponent. And it worked. There was violence between secular and islamist palestinian organisations.

But -shock horror- the islamists turned out to be a greater threat to israel than the secular fatah.

It's a little like 9/11. I vehemently disavow and condemn the attacks. But on the other hand, you kinda made your own bed so to speak.