[swaggyBoatswain]

Some people get paid to go to the conference and also for some its in their best interest to half pay attention while doing work.

On another level, sometimes I go to meetups in my area which are technically the same conference presentation as well. There are times when I regret going to the meetup (There's 10-20 people) because of how boring the speaker is or how overly technical it becomes, but I don't want to be rude and leave the area cause it'd reflect poorly. Its not like a convention where leaving is okay, everyone in the area knows each other.