Most pilots are completely addicted to coffee. Stand in the concourse at any airport and watch us arriving for our flights. If we work for a posh airline, one hand is pulling a rolling carry on bag with a leather case on top. The other hand clutches a cup of coffee. If we work for a scruffy company we're not on the concourse, and we're hauling a knapsack, but the coffee is ubiquitous. Part of it is the need to be sharp despite irregular hours and part of it is the culture.
Here's a conversation about flying the Airbus A320:
"So you set the autopilot through four hundred feet and then order your coffee?"
"Are you kidding? We set the autopilot right away. By four hundred feet we have the coffee in our hands."
Pilots drink coffee. We're expected to drink coffee. While we're waiting for the airplane, while we're waiting for the weather, or while we're waiting for the approach clearance. Even if you're not addicted to coffee, you drink it because everyone else is, and then you are addicted.
When I tried to kick the habit, it was like a well-known line from the movie Airplane, I picked the wrong week to give up coffee. I ended up flying with the chief pilot.
Very early one morning I was in a hotel lobby eating eating croissants and waiting for the rest of my crew, when I saw a uniformed pilot from another company. I made a generic comment of greeting, along the lines of "Good morning, what are you flying?" After a dismissive grunt, he declined to acknowledge me further. He pushed past me and went up to the reception desk to complain loudly about there being no coffee left.
Later, on the van to the airport, one of my crew turned to start a conversation with Captain Too-Good-To-Talk-To-Aviatrix. I was about to warn him, but to my surprise he answered my colleague quite civilly. And then I realized, he was now holding a cup of coffee. It really should be on our checklists.