Top caffeine drinkers are smokers with mental illness

Duh. Caffeine mimics serotonin. Smoking boosts niacinamide (aka nicotinamide, vitamin B3) signalling.

The two main paths for tryptophan metabolism are [majority] niacinamide/kynurenine synthesis and [minority] serotonin synthesis.

Heavy niacinamide/kynurenine demand diverts tryptophan from serotonin production, leads to chronically low serotonin.

Caffeine disrupts adenosine.

Yet another article that conflates coffee and caffeine

Most of the world ain't drinkin Mate, mate.

And while there is a non-trivial amount of caffine coming from other places like tea, or Monster energy drinks, I'd bet my hat that most of N. America is drinking coffee more than any other caffeinated beverage.

in my experience caffeine is not the bad stuff in Monster energy drinks

It's also not the bad stuff in coffee.

I quit caffeine cold turkey more than a year ago. I rarely drank soda and energy drinks before so most of the caffeine intake was through coffee. The first four months were the worst because of brain fog. But it also made me aware how badly addicted I was to caffeine!

I am all of these things (although not a smoker!) and consume way too much caffeine. Article checks out lol