As other mention, in a short sale, the owner is not making a profit, they are selling because they are falling behind on their mortgage or are about it. Short sale in the step before the bank forecloses on the property, which typically takes time to happen. The bank lent a certain amount of money for the purchase of the home and they want the remaining balance paid, thus the seller needs to sell and come up with other cash to pay-off the loan. Going into foreclosure and short sales will also hurt your credit rating. This process takes time, banks need people to review files and contracts. Short sale is a misnaming of the process, it should be called long sale. The short sale process typically takes 3+ month and is a longer process than a normal sale.
Hope this helps.