I know what you mean about assuming motives for the leaderboards. I’ve accidentally ended up in the #1 on leaderboards before. And when I say accidentally, I mean I wasn’t even trying to get on the leaderboard:
(Example 1) by submitting several observations to a taxon without many total observations. At the time, there were only around 20 observations of genus Podagrion, and I had submitted 4 of those, with IDs on those 4 and others, which made me suddenly the top Identifier.
(Example 2) By agreeing to the ID as a way of favoriting an observation which was, at the time, the only observation for that taxon. I’m not surprised that put me on the leaderboard, but I was the third person to ID that observation; the first or second Identifier should have been above me on the leaderboard.