Because he lost on survivor.
No, sorry I didn't explain this better. There are three stages in all their lives, and in each stage they live someplace different. Stage one is childhood- the first eighteen years of their life are spent as a normal child in Kindropolis. Then the next 22 (from age 18 to 40) are spent on the island of Hedonia, meant only for younger people. If there were more people on it than no one would run anything, parent the children, or sanitize telephones. Also, the island would soon be overcrowded. So, once you have turned fourty you move on to your next stage.