What is the origin of the idiom "have it made" and when to use it?

The idiom "have it made" means to be in a position where one's success is guaranteed. The phrase is believed to have originated in the United States in the early 20th century. It is thought to be derived from the phrase "make it," which was used to describe someone who had achieved success in life. The phrase "have it made" became popular in the 1950s and 1960s, and it is still used today to describe someone who is in a position of success.