While your offer of a free lunch may seem enticing at first glance, there is a great opportunity cost involved for me. To explain a bit further; if I don't attend then I will not get a free lunch but if I do attend I will need to spend time with you.
I'm sure you can see my dilemma here.
While it's a well-known fact that I deal with corporate idiots over the course of each event (for multiple events each year), you may be overlooking the fact that I get paid to do this. This is in fact my job and they pay me in compensation for my time and they tend to feed me too, so it turns out to be a much better proposition than what you have given me.
I'll be dining in hell in 5-10 years when I go on a murderous rampage killing everyone in my office, so perhaps I'll see you there?