How was Israel caught napping?

Any visitor to Israel notices almost on arrival that the country is tiny, wedged in with enemies looking over its borders which is why security is always at a heightened level of alert for potential attacks. Every day Israel is in a state of what one can only call attack-expectancy. So how could the Hamas militants from Gaza have mounted such a huge attack on Israel, not just with thousands of rockets but with ground fighters, heavily armed, who crossed the border and seized villages and hostages and killed dozens and wounded hundreds. How could Israeli intelligence have failed to spot the Hamas invasion build-up and how was it possible that so many of them managed to breach the border without being fired on? What has happened to the famously alert Israeli Defence Force (IDF). And why didn't the Americans spot what was going on from satellite imagery? Is it possible that Israel, including the IDF, had become so overwhelmed and divided by the extremist nature of the new Bibi Netanyahu government - masses of reservist forces had refused to honour their tours of duty out of opposition to Netanyahu's decision to emasculate the Supreme Court - that they had become less alert to the constant dangers facing the country, even perhaps a little complacent out of anger at the new government? Once the latest attacks are over, there are going to be huge repercussions for Netanyahu. He is the prime minister, he will ultimately take the blame and could be toppled once again.