I want to thank everyone for your input.
There were a number of good points made and it gave me a lot to think about.
I really had to consider the whole "networking" possibilities option for a while.
Turns out I had some bias to overcome, because I'd had a knee-jerk opinion of "I won't want to network with anyone at this event because I don't like the event, therefore no-one worth networking will be there anyway."
It came as a bit of a surprise to dig down and realize that I'd jumped to that (incorrect) conclusion. The event is also very business focussed and would probably have some people there for the same reason I would: to see and be seen.
So I really had to weigh that factor and reconsider it.
In other considerations, I really didn't want to give up a day's pay, and I've come to realize I feel pretty strongly about this.
It's a bigger issue that I initially thought, since it's really not done in this industry.
However - today was my performance review, and it helped clear some things up.
On the plus side, it was a very positive review, which was encouraging.
(My supervisor is actually probably one of the best I've had. We don't always see eye to eye, but she's fair, clear, supportive of us and has a good sense of humour.)
I felt the review was very fair in showing me what I do well and what I can work on.
We also discussed my future.
At this point in time, the central issue as to whether or not I stay on is based solely on whether or not there is work for me.
I'm confident that the company is looking at all the possibilities and what I bring to the table.
I'd love it if company goes ahead with [Project] and I get to stay on as part of it. I was part of the team that started it and getting paid to work on [Project] would fulfill a long-term goal of mine.
At this point, if circumstances permit, I would almost certainly be asked to stay.
Having said that, it does take some pressure off to "be a team player" and attend the event since I don't think it is going to affect my career path either way. (One item on my review was that the company appreciated that I fully participated in and was a part of everything the company does, even though I'm on a temp contract. So...I have been doing a lot of "team player" stuff and the company has noticed. I got high marks for this!)
I think I've decided not to attend. I'm not comfortable not getting paid when all the others are.
I think I will say that while I appreciate the opportunity, I'm not comfortable with losing the pay.
Thanks everyone. Getting outside opinions on how my behaviour could be viewed has been very helpful.