Well, sure. In the limit, I'd be sad if a large portion of humanity chose to use the experience machine [1]. More realistically, I'm sad that Americans spend so much time watching TV, even if it makes them happy.

I think I can at once support this guy's ability to make choices for himself and be saddened that our culture may have socialized him into making a tradeoff that I don't think was worthwhile, in some objective sense.

Perhaps the test I mean is, suppose football didn't exist and then you walked up to this guy in the present day, explained what football is, and then gave him the choice to relive his life starting from high school, but this time with football and all the (positive and negative) consequences he faced. It seems likely to me that he'd reject this out of hand.

[1] http://en.wikipedia.org/wiki/Experience_machine

I'm sad that people incur permanent, potentially life changing injuries from the game, not because I want to push my views on them.