Muslim nations have invested $5 trillion spreak over US govt securities, swiss and luxembourg banks, UK govt securities, etc. So they can live and eat for generations with interest alone.
BTW oil in Saudi arabia will last 40 years by present consumption. Beneath this oil there is thicker oil which is hard to purify and expensive. I am sure multinational oil giants by 2040 will figure out how to use this as well. This deposit is 10 times the deposit of normal oil.
And dont forget evergreen Toursim in Saudi Arabia. 25 million tourists visit Saudi Arabia every year bringing in cash dollars and euros.
