I remember back around the turn of the millenium I used to run the sidelines at Ballymore Rugby Union matches. I was using my FA 200/2.8, but there was a Canon lad there with one of those 200/1.8, and a 400/2.8 hanging around his neck. Damn impressive chunk of glass to see in the flesh.
Canon also had a 50mm/F1.0 I believe.
All's possible with untold wealth at ones disposal..
Look at the Sigma 200-500/F2.8 for example... Got a spare $32000.00 hanging around. Google it, pics of guys holding it like a trophy fish.
Its a monster!!!