It's well possible that Magnus and Anand and cohort are having the lifestyles of active sportsmen with nutritionists and physical trainers and all that good stuff, while amphetamins or at least Provigil is rampant among middling players breaking into the middle ranks.
I've been in a 52-versus-one simultaneous (offline) game with a Champion (not a Grand Champion). I'm mediocre at chess, but can you imagine the kind of skills you need to beat 52 mediocre-to-interested-amateur players? At Magnus's level stimulants possibly no longer work -- much like amphetamines wouldn't help me pass a calculus exam; probably even set me back.
I've been in a 52-versus-one simultaneous (offline) game with a Champion (not a Grand Champion). I'm mediocre at chess, but can you imagine the kind of skills you need to beat 52 mediocre-to-interested-amateur players? At Magnus's level stimulants possibly no longer work -- much like amphetamines wouldn't help me pass a calculus exam; probably even set me back.