They have so much wealth that they don't know where to invest their money. Yeah, let see how it goes, if those rich prince or sheikh decided to invest in bitcoin then good for the bitcoin ecosystem. Otherwise, bitcoin is already doing fine as of the moment but if Middle East want's to join the fun, the better for us.
but i wonder what proportion of saudis have real money. you got the governing class of course who are crazy rich. i kind of get the impression everyone else is sitting around doing nothing being given oil money, but maybe not a great deal of it.