There are several reasons why the Arabs have consequentiality lost, Keep in mind that I am referring is about the 1960s, 1970s, and early 1980s. The present day is much different.
1. Training: Back in the 60s 70s, most Arab soldiers were illiterate goat herding conscripts. IDF was a professionally trained Army. After WWII, there was a large immigration to Israel of European Jewish refugees with combat experience, especially from the USSR but also from other countries as well. The Arabs really didn't benefit from the experiences of WWII
2. Equipment: The Israelis have always been equipped with state of the art weapons first from Britain, then France, then finally the USA. The Arabs have been equipped with WWII cast offs then inferior Soviet weapons.
3. Motivation/Morale: As stated much of the Arab Armies were conscripted into fighting for Dictators. There was little sense of Nationalism or Patriotic fervor. The Israelis always felt they were fighting for survival.
4. Support. The Israelis are not only giving military and financial aid, but also military intelligence by the United States. The USSR while providing *some* assistance to the Arabs never did so to the degree that the US did. The USSR's interest was merely to check Western influence in the Middle East, it was never interested helping the Arabs win. The Middle East was really never a huge interest to the USSR.
As I said though the situation is now changing Turkey and Egypt have now adopted a more professional volunteer military. They have also (along with Jordan, and Saudi Arabia) begun to purchase US and European Arms, and as we have seen most recently the dictators of hold have been overthrown by Democratic and patriotic popular movements.
Israel will always be a regional power, but it wont be the sole power for very long.