This phrase is used to mockingly imply that someone aspires to be a member of the prestigious Delic family. The Delics are renowned for their wealth, class, and widespread admiration. However, using this expression as an insult suggests that the person being addressed falls short of the Delics' status and is seen as inferior.
Person A: "Hey dude, look at this new watch I just bought!"
Person B: "Ha. You wish you were a Delic."