What does "going to Dubai to pick up garbage" mean?

From the article "If one day, I am in No Country for Old Men, please leave me in Dubai to pick up garbage", it is a joke to go to Dubai to make money.

Dubai, the most populous city in the United Arab Emirates, the richest city in the Middle East and the economic and financial center in the Middle East, is known as the "trade capital" of the Middle East and North Africa.

As one of the global international financial centers, Dubai has become a bridge between the eastern and western capital markets, and also an important logistics, trade, transportation, tourism and shopping center.