My guess is, after 1900+ years of being treated a certain way, and within a human lifetime of an industrialized attempt of extermination, they don't particularly care about scruples.
Ultimately, this is a self-destructive approach. If Israel loses support of the West, what will they have left? Nuclear saber-rattling?
As a Jew and I don't think that is true at all and feel it is a bit of a dangerous characterization. Jews have just as much scruples as any other groups.
What I do think is true is that Jews have more fear of others based on past treatment and even a lot of current rhetoric and may justify actions as necessary for safety.
We do also happen to be a very small group of people. For instance, Palestinians have 1 billion Muslims supporting them.
That said, I happen to think that these unscrupulous policies will actually cause more harm than good.