I know it's senseless. I know it's unreasonable. I know it's unhealthy. There is, objectively, no reason to be in a bad mood because I lost a game being played for fun that has no stakes attached.
To be clear, this isn't directed at the person who beat me (unless it's someone who's really rubbing my face in it). I want to win, I'm doing my best to win, I wouldn't ask them to do any less, and I wouldn't get any satisfaction from a victory against someone who was pulling their punches anyway. My negative feelings are largely directed inward: when I lose, I feel like a failure even though I intellectually understand that you'd have to be a complete tool to judge anyone else so harshly for losing at a game.
I've been like this as long as I can remember. I've definitely gotten a much better handle on my emotions when I was young, but I'm sure it it still comes through, even if people don't say anything. It's not fair to the people I play with, and I wish I wasn't this way. I actually greatly prefer cooperative games over competitive games because of this, because that way if I lose, the other player(s) is/are in the same boat - we all failed together, so I can't be judged negatively in comparison to anyone.
Anyone else have similar issues? Anyone who can offer insight as to why I might feel this way?
You know how Kauffman did humor, where the real punchline isn't the joke, but your reaction to it?
Try seeing games like that. Yes youre trying to win, but that objective is just a vehicle for the real objective of having fun. See if you can pull weird shit and win with it. There was a pro StarCraft player who played like this; I forget their name. Basically, find the weird shit that shouldn't work, and find ways to make it work, instead of standard sensible builds/loadouts/strategies. See if thats more fun on balance. Certainly makes the world weirder for everyone around you.