Anecdotes it is. Quit caffeine in 2015. I was drinking coffee and red bull constantly. Felt like crap for about two weeks. Measurably no difference other than b

Anecdotes it is. Quit caffeine in 2015. I was drinking coffee and red bull constantly. Felt like crap for about two weeks. Measurably no difference other than bank balance. Did a crap action film montage in 2019 and went from lard ass to super fit. Massive positive change in cognitive ability and mental health. Started drinking coffee again in 2021. Absolutely no change other than bank balance. Only difference is I keep it to one in the morning now and occasionally swap it for a hot chocolate if I fancy one. And only for the bank balance. Ergo I suspect the best software developers are the fit and healthy ones.