Two friends, Joe and Brad, each put $20 into a black box.

The box now has $40 in it.

Joe then buys the box from Brad for $30. Joe walks away, happy that he got a $40 box for $30; Brad walks away, happy that he got $30 for the $20 he put in. Both men gained $10 from this transaction. Lolwut?

Joe actually lost money .... Joe paid $50 for his $40 box --- $20 he put in the box & $30 he paid to buy the box

Joe can probably make it up in volume!