There's been only a select few QB's that have had the playing time in the NFL that Brady has had & nearly all of them are in the Hall of Fame, I dont see it quite that way TBH. (I'm pretty bad at playing sports BTW) If I was a successful NFL quarterback that has played for as long as he has, to play every week From August (pre-season) into February (Five months) & you have the ball for a few seconds for let's say 30-40 times a game, before three or four blokes over 6ft tall weighing 20-25 stone screaming obscenities at you & trying to land on top of you or push you to the ground while you still have the ball, I think that would be a little tiring. Once I'd reach 40 or so (I'm 53 BTW) & I'd rather be teaching the youngsters the tricks of the trade of being a top QB. All that time out there its going to take its toll in later life.
Personally (and maybe this might be because you say you're not good at sports) but my mind just wouldn't work that way. I loved playing. I actually sat in my car and cried when the Doc said I had to stop
To me, I can't comprehend why Tom B would just decide to stop playing if he still can at that level. What he's achieved is pretty much irrelevant. I get it when they're past their prime, like Manning clealy was, you hope they can see this and hang up their boots, but even then, that's a tough thing to do when you love playing.
I also don't really get the whole 'amount of seconds you hold the ball in a game' point? My career was probably 40% QB, 40% FS, 15% HB and 5% DE. 45% of my career I barely touched the ball each game! Why does that matter?