GMS PLAYING BLITZ/BULLET

I find it very interesting that all the IMs, GMs, etc. play speed chess all the time (bullet/blitz) A LOT!  Isn't speed chess detrimental to one's game? I know the go to line is,"well they do it to avoid engines(cheaters)".  Which I would buy if speed chess was just a fun thing to do that had no effect on one's game.  It just doesn't make sense that all the high level players spend copious amounts of time doing something that would have a detrimental effect on their LIVELIHOOD!  No?  BTW, as a side note, I am not a speed chess player at all. I usually stick to twenty minute games.  I just dont see Peyton Manning or Tom brady doing something for "fun" all the time that has a definite hurtful effect on their accuracy as nfl passers! Ya dig?