Not to be stereo typing but why are most Arabs I see So rich?

So I went to the mall today to shop and I saw an 8 year old wearing gucci and playing with an iPhone 5. I was like don't see that everyday. & I went to the Louis Vuitton store & Prads and EVERYONE WAS ARAB. I go outside and see amazing cars such as Bentleys, mercedes, bmws, and all them are Arab! I understand most of it's from oil but how? How does the government gaining from oil have to do with all these rich citizens that now have migrated here? It's crazy and I know not all Arabs are rich. I've seen places such as Palestine but I'm just wondering.

Only the rich ones can afford to travel to your shopping mall. The poor ones are living hand to mouth in the Middle East.

Because the UK filters out broke Arabs.