Why is Bahrain so prosperous?

Becouse it is called Kingdom of Bahrain and has a KING - stupid!

Bahrain, officially the Kingdom of Bahrain (Arabic: مملكة البحرين Mamlakat al-Baḥrayn), is a borderless island country in the Persian Gulf and is the smallest Arab state. Saudi Arabia lies to the west and is connected to Bahrain by the King Fahd Causeway (officially opened on November 25, 1986), and Qatar is to the south across the Gulf of Bahrain. The Qatar–Bahrain Friendship Bridge being planned will link Bahrain to Qatar as the longest fixed link in the world.