I could make financial excuses (my luxury budget is pretty flat right now), but they really aren't primary. My luxury budget wouldn't be flat if I'd been planning to attend; I decided a while ago I wasn't.
"I can't afford the high chance of getting sick" is a lot more significant. Last year, I had to miss a week of work because I got sick with something unknown, and whatever it was, I was already feeling the effects by Sunday- when the first day I attended was Saturday. I don't have a lot of trust in my immune system, and that certainly didn't give me any reason to have extra faith in it. Work is unreasonably stressful right now, which also decreases the effectiveness of my immune system, and the reasons that make it stressful are exactly the reasons I can't miss a week.
I ignored exactly that last year (although work wasn't going as badly at that time); the balance is different this time in large part because I don't like the theme. Zombies are not my thing. There will be other years, so a poorly-timed weekend event highly likely to make me ill has to do better with its theme than "maybe it won't be applied too heavily and I can ignore it".
I'll spend the weekend catching up on the laundry backlog, catching up on the cleaning backlog, reading, and cooking. (I'd also like to do a few Tarot readings, so if anybody's interested, please let me know.) Maybe I'll catch some of y'all next year.