I'm kind of surprised no one reported this but I also initially assumed more people were zapping posts than me and I just wasn't qualifying.
The next experiment we'll probably run will randomly reward one of:
  1. top posts
  2. top comments
  3. top zappers
... everyday. This way regardless of your economic strategy you'll get some sats so long as you regularly participate and when you get them they'll be 3x larger than if they were evenly divided between activities. Also randomness is more fun.