They went aggressive defense, after the effects of WW2. They built an impressive machine to both keep themselves safe (by all means necessary) and hunt down Nazis who fled into hiding.
Unfortunately, they ran out of targets, on the nazi front, and really pissed off their neighbours. Rather than risk de-escalating, they've gone all-in.
The intergenerational changeover, and the political games that entailed lead to the current situation.
Stare too long into the abyss, and the abyss will stare back into you.
Give it a break. One of Israel's staunchest allies since the start was West Germany - which enthusiastically co-operated with Israel while Israel was fully aware that it's intelligence services were jam-packed with nazis. Israel only hunted the nazis that were convenient to hunt.
The ones working for west Germany, as well as America weren't hiding, they were useful. Their targets were the one who were useless alive for anything other than getting revenge against.
The key is they had a good excuse to build a highly effective surveillance and infiltration system. It also was/is skilled at getting their hands dirty on foreign soil, while keeping the mess contained. At the time, they have a worthy target. As time went on, the number of targets dropped. The system in place was then turned to other uses.
The whole point of the state of Israel is to have an ethnostate - at the minimum, apartheid, at the maximum, genocide - which is why there is a huge split among Jewish people worldwide as to whether or not be Zionists.