Because they've been persecuted, scapegoated, and killed everywhere they've gone for thousands of years. Then we give them a tiny slice of desert and all Hell breaks loose. Every other ethnic group has somewhere they can go and feel safe. Most of The Old Testament isn't a historical document but there are historical documents and artifacts that trace their history to that part of the world centuries before Islam existed.
There's a great book called 'The History of the Middle East' by Peter Mansfield.
I'd urge anyone with even half an interest in what's happening to give it a read. I was given a copy a few years back by a friend - and it's certainly opened my eyes to what's happening. You need to understand the history of how Israel came to be in order to comprehend the chaos we're seeing now.
Some take-away bits:
Most sane people knew Israel would never work, even before it was ever really put in motion - when there were just 10,000 Israelis farming small plots of land around the turn of the 20th century - surrounded by just under 1 million Arabs.
When the idea was proposed, most American Jews were completely against the idea - so much so that the USA never even sent a delegation to check it out - that's how unconvinced they were.
The main bone of contention all boils down to immigration. Many times, the surrounding Arab countries said "okay - but there must be a limit on how many Jews arrive each year - in order to keep things balanced in favour of the Arab populations. Israel continually ignored this and just kept sending them over - well in excess of whatever quota they'd been given. This kept going on for decades, until the point where the Arab states lost faith in Israel (and the Western governments that supported it) because they believed they couldn't trust them at their word.
It is way, way, way more complicated than this - but ultimately, I find it hard to not see what Israel is doing (and has been doing) to Palestine as EXACTLY the same as what the Nazis did to them. No "war" can justify the mass murder of over 10,000 women and children "in the name of terror". What we are seeing is a war crime - or let's be more specific here; ethnic cleansing - because there's no other plausible explanation.
But what about the brutality of Hamas' attacks? Indeed - but who made Hamas? People don't wake up psychotic bloodthirsty murderers - that tends to happen over an extended period of suffering. To quote the UN chief - it didn't happen in a vacuum.
Right at the very beginning the alternative location they were offered was somewhere in Uganda - and wouldn't that have made much more sense? All this death over a religious site that is, for all intents and purposes, just rubble and rocks and buildings that have been built and demolished and then rebuilt over and over again over thousands of years.