In fact, a great deal of the land purchased was not then in use by the Arabs and while there were purchases from absentee land owners, these land owners were generally Arabs, not Turks. Just as in England in the 19th century the wealthy might own land in several areas but would prefer some sophisticated city as the prime residence, there were Arabs who owned land in what is now Israel but who greatly preferred Cairo as a place to live.
One major issue later, but not at the time, was when Jews began draining swamps and otherwise developing land which had long been of no value, as there were never enough people to bother with developing it, even presuming that the scientific knowledge for doing so had been available. Evidence suggests that population in the region was stagnant and had been for quite some time, which is one reason even a small Jewish influx might have been noticeable. And draining or otherwise developing land clearly presumes a surplus population willing to farm the land.
As any Dutchman knows, such swampland is exceptionally fertile once drained, and it is easy to see people who thought they were getting the better part of the bargain learning that they badly underestimated the potential value of what was sold.
As for Arabs losing their jobs, not a possibility. Until the 1920s, there weren't enough Jews there to TAKE anyone's job, less than 100,000 and given the establishment of communities in Jerusalem, Haifa, and Tel Aviv PLUS the four ancient religious towns it's hard to see just how many farmers there were. And after this period the Arabs became much more opposed to such land sales.
As a side note, one reason that so many German Jews were reluctant to flee is that the behavior of Nazi Germany was considered to a complete reversal of German attitude for centuries. Of course, where were they to go, given global restrictions on immigration.
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