What the Arabs decided is to start a war to detroy the future Israeli state and take all of Palestine for themselves. You also need to read some history other than that rewritten by the Arabs and the far Left. The truth is far different.
First to leave were roughly 30,000 wealthy Arabs who anticipated the upcoming war and fled to neighboring Arab countries to await its end. Less affluent Arabs from the mixed cities of Palestine moved to all-Arab towns to stay with relatives or friends. Joseph Schechtman, The Refugee in the World, (NY: A.S. Barnes and Co., 1963), p. 184.
Time Magazine reported on the battle for Haifa (May 3, 1948) by saying: "The mass evacuation, prompted partly by fear, partly by orders of Arab leaders, left the Arab quarter of Haifa a ghost city....By withdrawing Arab workers their leaders hoped to paralyze Haifa."
Benny Morris, one of the Israeli "New Historians" who documented instances where Palestinians were expelled, also found that Arab leaders encouraged their people to leave. The Arab National Committee in Jerusalem, following the March 8, 1948, instructions of the Arab Higher Committee, ordered women, children and the elderly in various parts of Jerusalem to leave their homes: "Any opposition to this order...is an obstacle to the holy war...and will hamper the operations of the fighters in these districts" (Middle Eastern Studies, January 1986).
Morris also said that in early May units of the Arab Legion reportedly ordered the evacuation of all women and children from the town of Beisan. The Arab Liberation Army was also reported to have ordered the evacuation of another village south of Haifa. The departure of the women and children, Morris says, "tended to sap the morale of the menfolk who were left behind to guard the homes and fields, contributing ultimately to the final evacuation of villages. Such two-tier evacuation —— women and children first, the men following weeks later —— occurred in Qumiya in the Jezreel Valley, among the Awarna bedouin in Haifa Bay and in various other places."
The Secretary of the Arab League Office in London, Edward Atiyah, wrote in his book, The Arabs: "This wholesale exodus was due partly to the belief of the Arabs, encouraged by the boastings of an unrealistic Arabic press and the irresponsible utterances of some of the Arab leaders that it could be only a matter of weeks before the Jews were defeated by the armies of the Arab States and the Palestinian Arabs enabled to re ?enter and retake possession of their country." Edward Atiyah, The Arabs, (London: Penguin Books, 1955), p. 183.
In his memoirs, Haled al Azm, the Syrian Prime Minister in 1948-49, also admitted the Arab role in persuading the refugees to leave:
““Since 1948 we have been demanding the return of the refugees to their homes. But we ourselves are the ones who encouraged them to leave. Only a few months separated our call to them to leave and our appeal to the United Nations to resolve on their return.”” The Memoirs of Haled al Azm, (Beirut, 1973), Part 1, pp. 386-387.
"The Arab States encouraged the Palestine Arabs to leave their homes temporarily in order to be out of the way of the Arab invasion armies," Filastin (February 19, 1949) (published in Jordan).
"The Arab government told us: Get out so that we can get in. So we got out, but they did not get in." A refugee quoted in Ad Difaa
(September 6, 1954).
There is much more where this came from.
40-60 thousand Arabs left of their own accord. Some (20-30 thousand) were forcibly moved. The rest (most of them) ran from battles and war zones.