My simple logic is, as an example, $-3.2B < $-3B by $200M; hence the transaction is more "profitable". In other words, the player is less in debt compared to if they sell the item for near market price. If the remaining debt was later removed/cleared, the transaction itself is still profitable (at the time it's executed) but the overall impact to the player is nil.
I should mention that putting an item to sell above market price doesn't make it profitable unless someone is willing to buy it at the list price. Buyers are not obligated to accept the price sellers asked so there's nothing wrong to list items at $20-30M above market value. Each player has total and complete autonomy and agency to NOT click the buy button and if they do, they voluntarily agree to pay the price sellers asked. It's how a free economy works after all.