Why is Dubai so rich without oil?

I don't understand Dubai economy. Yeah, it's port city but there are so many of them in the world like how exactly it does do which makes so rich and lucrative to move to despite bad climate and major restrictions.

Why is Dubai so rich seriously? Like is it feeding it's wealth on rest of UAE oil reserves or something if so, how sustainable and self sufficient it is in future?

Also one more question, if it's some tax heaven thing again, why can't other countries set up these? Like why hasn't anyone else copied Dubai model whatever it is?