I got this message:

SubetaTeam bought your Papku from Eudaemonia: Shop of Wonders! for 475,000sP. The sP has been put with your onhand sP.

Why is there a special message for this? And why would the admins buy an item from me? (and why doesn't it go in my profits?)

Sometimes the Subeta Team buy underinflated items to make the prices of the item rise to a more stable average-price level.

The SubetaTeam buys Donation Presents that have been drastically underpriced. The money goes directly into your onhand till.

Thanks! That makes sense.

This time around they bought some ordinary non-DP items (mostly elixirs), too.