It's unfortunate that some can't understand an individual's emotions when faced with the realisation that one of the things you love doing the most and have dedicated your life to is, premetually, taken away from you. He is only 31 and to draw a comparison, Roger Federer is 37 and still playing.
Like him or loathe him, we are all different and should, at the very least, be able to respect the other person's reaction to a situation, empathy springs to mind. To him, I suspect, it must feel similar to a bereavement, a loss.
For professional sports people, it's not all about the money, for those that haven't played sport at a professional level, I can understand why they might think it would be.