Why is everyone still being so optimistic that Sidney Crosby will come back and play again after sustaining a.?

.concussion/s (1/1 and/or 5/11) and post concussion syndrome (1/6/11). The question also applies to other hockey players and other players in other sports as well. The questioner isn't even a fan of his or Penguins as well. But just been following all of the him because of his concussion/s and post concussion syndrome. At the same time whom knows when he will total symptom free from all of this. Since concussions and post concussion syndrome are totally different then other types of injuries.