I think you're confusing their actual personality with their personality during competition. Usually tiger after he plays is not very happy. Whenever you watch tiger in a more relaxed environment he's always quite entertaining. Now it's clear you don't watch much golf and you probably just see his interviews on sportscenter so it would be like me commenting on nascar drivers personalities. He's been known as one of the funniest guys as well as one of the biggest pranksters on tour.