I don't think they miscalculated. Almost everything in this benefit them in almost every possible ways. The horrors of Gaza makes them almost look nice to the eyes of some (they never have been more popular in Palestine and in the world), and makes sure they will have no shortage of terrorists in the many years to come, among the innocent victims and their brothers and sons/orphans. I don't imagine they care or didn't anticipate for those killing of innocent people.