That seems very obviously not true, unless by "primadonna athletes" you mean "the vast majority of athletes". Athletes face opportunity costs just like the rest of us, and different athletes come to different priorities. They aren't robots.

For instance, stories about pro athletes coming to training camp out of shape are very common. An article I recently read about Andre Miller comes to mind. Andre Miller is a basketball player that most would say fits the archetype of "wily veteran" rather than "primadonna". How does he train? http://espn.go.com/blog/truehoop/post/_/id/15542/the-secrets...

"I have no regimen," Miller says. After the season ends, so does Miller's working out -- no weights, no cardio, no nothing. "I really don't pick up a basketball." Eating right also falls by the wayside. "(My diet) isn't healthy at all," Miller says. "Hamburgers, hot links on the Fourth of July, all that." To control his weight, however, Miller uses old-fashioned discipline. "I starve myself," he says. Seriously? "Yeah, I'm just starting to learn about calories and all that."

Yep, that's the guy who owns the active NBA record for consecutive games played. And he competes against players like Kobe Bryant and Steve Nash who are famous for their impeccable training regimens.

Another example... literally every female athlete who gets pregnant is hurting her chances for victory. Yet tons of them do it.

That isn't clear-cut. There are rumours that getting pregnat was used as a form of doping. See http://www.snopes.com/politics/sexuality/doping.asp, http://en.wikipedia.org/wiki/Abortion_doping