Well, originally to get poon. Then I joined the Marines and felt it made my job easier to be big and imposing. After I got out it was back to poon. From there I got married. Now I'm so accustomed to being big that I'd probably kill myself if i got smaller.
I also get Bulk Nutrition prices at my neighborhood GNC because I help the owner's out with training, nutrition, ect.
Life IMO is a lot easier being big. You don't get into fights anymore because people assume that if you're big then you can fight.