Because most of them know when they go back SA, their daddy the sheik will get them a secure job where they just have to show up to pick up a paycheck. How do I know this? I have an in-law who worked for a Mideast oil company. The only people who did any work were the Europeans and the (east) Indians. The locals just showed up to get their guaranteed paychecks. Why they had to go to school when their pay was guaranteed, I don't know.
I believe that there is still a poor underclass in Saudi Arabia. I am sure that the attitude of superiority amongst many of the wealthy is also expressed onto the poor in SA. I feel sorry for them. As Christianity covertly expands in SA, I am certain that many poor will come to Christ.