We must not forget that if Israel wanted to actually wipe out Hamas, they would have already done so. When the Yom Kippur war ended on the 25th of October 1973, Israel's armies were already on the other side of the Suez Canal. By the time the Egyptian army reached the Suez Canal they were already surrounded by Israeli troops. If Russia and China would not have pressured Israel to stop fighting they would have easily wiped their neighboring countries off the map. Israel was being attacked from the North and the South by Iraq, Egypt and Syria. Instead of winning with three to one, they actually lost land. Israel now possessed Syrian and Egyptian territory.

In 19 days Israel stopped and pushed back the invading armies. The Arabian side lost 15.000 soldiers (another 35.000 wounded), 2250 tanks and 432 aircraft.
Israel won the war and they were actually forced to return the occupied territory to Syria (by Russia and China). just to be clear: Israel occupied so much territory their artillery was now in range of Damascus. +- 40km away from Damascus. When the UN finally interfered and stopped the war (mostly because of China and Russia) Israel was 101km from Cairo, the Egyptian capital.
Troops:
Israel - Arabian world
troops: 415.000 - 1.000.000
Tanks: 1500 - 4500
vehicles: 3000 - 3500
Artillery: 945 - 1490
Aircraft: 516 - 584
Helicopters: 4 - 197
Ships: 38 - 125
The point I am trying to make: If Israel wanted to completely remove Hamas from Gaza and the West-Bank, they would have done it by now. Hamas' rich friends on the other side of the Middle-East have left the Palestinians to die.