I think they are speaking not of regular iNat users but of those who only come for those few days of the CNC then disappear never to be seen again.
Aarav is saying their motivation for participating those few days is winning, thus they disappear.
squidtk posits that they take time out of their busy schedules in response to a plea from iNaturalist for “a photo of a bug.”
That said, we are asked not to ascribe motivations to others.
(Like you, though, I participate normally during these.)