Short answer: Oil
Long answer: Oil and foreign expertise and labor
Oh well, I guess it also helps that it's somewhat less draconian at imposing their religion based laws. Otherwise the Dubai Portapotties wouldn't be able to earn their living and will have to settle for Onlyfans.

There are many oil rich rich countries like Dubai but they could not make such huge progress because they are politically not stable and leadership is corrupt so oil is not the only reason for their fast development. There are many other reasons and one of them is Dedicated and forward looking leadership who has smartly used Dubai oil wealth, Western brain and Asian muscle to reach where they are now.