The caffeine and sugar intake is higher than any other time of the year. People are getting buzzed and tweaked.
People aren't just demanding, and pissy when someone else takes their drink, or their drink is wrong.
People glare. While I was on bar, I'd be glared at by at least half customers. Sometimes they would remind me what their drink was. Sometimes they would tell me how to make it.
This is an amazing, unwarranted lack of distrust.
But I bet people feel very paranoid around this time. This is a time of great judgement: Is the present good enough, cost enough, Did I make dinner right, Do my grandkids really hate seeing me?
There's a lot of Mandatory Family Attendance. The holidays aren't about what you WANT to do, but enacting rituals which will, using Magical Thinking, result in Happiness or Comfort or a sense of Safety.
Believe me, it doesn't work.