I would imagine that to some degree, muscular guys/bodybuilders have a bit of an ego - I mean you basically have to if you're going to devote so much time and energy + blood/sweat/tears towards sculpting your body. It's practically a lifestyle change - diet and exercise/weighttraining to get built - so yea, I'd expect muscular guys to have some level of egotism if they pour so much time into molding their physiques.