Because there is no rational framework for their actions, understanding them is like grasping jelly.
In the same context, I submit to you the idea of understanding Bill Clinton.
except the jelly in that case is KY ;>
<< "we gave up trying to understand them." >>
I've spent years throughout Africa and the middle-east, have worked with many Israeli and other agents and know their MO's fairly well. My best picture was drawn for me, though, a few days after Orenthal James Simpson had murdered his former wife and the waiter unfortunate enough to be there at the time. I remarked to a retired Colorado Supreme Court judge that I couldn't "understand" how a "man" like Simpson could slaughter the mother of his children and leave her carcase lying in its blood and that of essentially a passing stranger. All of that within ten feet of where his children were sleeping -- and then drive home, take a shower and big-shot it off to Chicago to work as if nothing was amiss.
My friend asked me if I could have committed the murders and, when I said that of course I could not, pointed out that I would never need to nor ever could understand beyond that point and aught not waste my time trying.
Thus the final piece fell into place insofar as the Israeli and other agents' attitudes -- and policies -- were concerned.
It was and is an absolute impossibility and thus an absolute waste of time to try and understand evil. Sufficient that we recognize it.
And kill it.