Tonight, my friend Emily expressed great sadness over the fact that she had no upcoming events on Facebook. I told her I'd change that.
This event is open to anyone who wants to feel loved by seeing an upcoming event on the social calendar, fake as it may be.
If this problem doesn't affect you, then by all means decline the invitation. Make sure, though, that you remove it from your event list if you don't want to see it, as it will show up regardless of your response.