I've never really understood why people restrict themselves to trade.

The only reason I can think of for doing it is an unwillingness to hold cash for a period, as surely it requires the stars to align nicely that 2 people want the watch that the other has.

Similarly I've never understood why people put a higher trade value on a watch than the sale value as surely the person trading would do the same.

Of course it's possible that there's something magical happening with trades that has simply passed me by.