The 3 billion that goes to Israel is used to maintain its military edge over all of its neighbors. The 3 billion which goes to Egypt goes to the military-class to maintain its hold over the country.
The money to Egypt was promised by Carter to create a peace deal between Israel and Egypt. Frankly, there are like 15 countries in the Middle East. If we could just pay all of them 3 billion a year to bring peace there I would vote for that in a second.
Paying dictators ruins the lives of millions of Arabs. Many are imprisoned and tortured by the security state. The majority are condemned to lives where they can barely afford to live and have very little hope of educating their children to improve their outcomes.
But sure, keep pretending like the problems in the Middle East are just a few countries short of 3 billion.
I'm not saying the Middle East's problems are fixable with 3 billion a year. I'm saying 3 billion/country/year is cheap to fix problems in the Middle East. And it fixed the series of wars between Egypt and Israel that had lasted, what, a generation?
But yes, Syria is a mess and cannot be fixed by writing a check. Which is too bad, because it would be great if it could be. And the entire Arabian peninsula has too much money for a 3 billion/year bribe to change things. But if raising 3 billion a year could stop the suffering of millions of people in Syria, my guess is that it could be done very quickly.