Back in Beta, I recall seeing something suggesting that players get paid a tax on gates they contributed minerals to, probably with the intent of encouraging players to build gates other players will want to explore. This was different from the crowns you get for depositing minerals.
I've dug through the wiki and I can't find any reference to this. Am I imagining this, was this a feature that was cut prior to release, or does this still exist?
Yes, you did get paid a sort of profit depending on how many minerals you donated to a gate. I think you got a notification every 24 hours or so, when the gates would shift. There was also some sort of bonus for the "highest investor", as in, the one who threw in the most minerals.
Apparently, they have removed this feature. This is probably because you get paid straight fees now, upon donating minerals, rather than every set time.
The problem with a tax feature and a 'highest bidder' rewards on gates was that it encouraged passive play in that people would simply mass up tremendous amounts of minerals and just 'buy-out' a gate for the rewards. Payout-per-mineral ensures that all players are on an equal footing regardless of their gate building strategy (or lack thereof) and gives them a small incentive to collect minerals and turn them in regularly.
My friends and I were commenting on a few days ago, so you're not hallucinating (or at least, not doing so alone).