Dubai is the wealthiest city in the Middle East. It's the most prosperous city in the entire world! Dubai doesn't even have any oil left, but that's alright because only 2% of its GDP is from oil. The city is rich even still due to other things like tourism, trade, real estate, finance, and entertainment. They have their hand in everything, and it is working for them, quite obviously.
It's a beautiful city and yes, the very richest one in the world. There's a reason for that. They are entrepreneurs of the highest degree, and that has always been the spirit in the country. They certainly had riches come their way through oil, but they never leaned on oil. They kept making strides in other areas too, which have paid off greatly. They are well diversified, and they reap the benefits of being so.