The last wwdc i went to experienced a sharp decline in population after the keynote.
I understand the grumbling at the idiots that buy a $1600 ticket to watch the keynote, but I don't think there's that many people that truly impulse buy such a thing just to see the damn keynote. I've skipped out on half the keynotes so far to sleep in and eat breakfast and show up in time for the SOTUs in the afternoon instead, which are much more informational.