If they say that it’s income, then athletes can claim expenses associated with receiving that income. Equipment, ice rink rental, airfare, trainers, etc.
I’d think the cost of training far exceeds any worth of the medal. But once the endorsements kick in then it gets really positive for the athlete, as long as he/she is smart.
But what is you don’t win a medal but just minor prizes. Seems to me you could also deduct relevant expenses and run a loss. Hmmm.