Theory as to why this is: caffeine boosts serotonin and serotonin increases guy motility. The faster the food transits, the less you can absorb and you lose weight. Higher levels of serotonin also reduce sugar craving.
But 99% of my consumption is my own cold brew. No sugar, brewed very strong, and then with just enough milk to bring out the flavor.
By my anecdotal sampling a good portion of the population would never pay coffee shop prices for what they drink daily to function.
The fact that they have a big pot tells me there are others who get drip coffee.
How energy drinks etc fits in here, I don't know.