Excuse me? That is an extremely uneducated statement you just made. Are you familiar with a man named Sidney Crosby?
He skated for the first time since that hit two days ago, that hit was 3 months ago.
That is one of MANY examples, concussions are NO joke. Please tell me one person that has gotten a concussion and came back to play just days later, it doesn't happen.
Didn't Crosby keep playing after the hit by Hedman in the game where he was diagnosed with a concussion? Which was three days after the hit by Steckel in the Winter Classic? And didn't he look pretty fazed by that hit, like at the end of the game, not realizing that he should have skated onto the ice when his goalie came off? It seems like there's a decent chance he suffered a concussion then and just lied about it.
Didn't Ian Laperriere play in the preseason, lying to the Flyers about how he felt from taking those pucks in the face last year? And despite the fact that that he never recovered from the last one he took in the playoffs, he did come back and play with it in the playoffs too.
Last year a poll conducted by the AP showed that almost 20% of the NFL players surveyed had hidden concussion symptoms from their team. Before last year (I believe) players could return to a game as long as they hadn't lost consciousness. It was only a month ago that they established a standardized test for trainers or doctors to use to determine if a player might have a concussion.
Aaron Rodgers missed one game after he suffered a concussion against Detroit, but he didn't miss one after the concussion against Washington, earlier in the year.
In the NBA this year, Luc Richard Mbah a Moute of Milwaukee didn't miss a single game after suffering a concussion. He played three days later.
Players get concussed and come back days later (or just never leave the game, because the concussions aren't officially diagnosed) much more frequently than what you're suggesting.