Its continued existance in the middle of neighbours who would like to see it disappear has been achieved by great superiority in the methods and techniques of using deadly force.
You could have said the same of Sparta, Prussia, England, the Iroquois, early Rome, Macedonia (under Philip) or any other such aggressive, expansionist national entity in the annals of military history.
Plus...Israel has been massively funded and assisted from abroad, mostly from the USA. That always helps.
Whether or not occupying various pieces of land in the search for "lebensraum" is beneficial or prejudicial to the continued survival of an expansionist state can be debated until hell freezes over without anyone ever reaching a final conclusion on the matter.
One thing I do know. All such states are a plague upon their neighbours, and they eventually overreach themselves.
Here is an article on lebensraum, which might prove instructive: