You'll help sell the competition. Most buyers are competitive shoppers. Your home will stay on the market a long time. If you don't sell them then, it takes approximately three months to replace them with an equal number of newcomers. You'll lose market interest and qualified buyers.
Serious buyers use the value, quality and price of similar properties as deciding factors.
A negative impression is created. People will wonder why your house is still on the market - They'll believe something is wrong with your home. You may have to make extra mortgage payments as well as incur taxes, insurance and unplanned maintenance costs. Studies show that the longer a house is on the market, the greater the discount off the list price. Often a seller will accept less than fair market value in order to sell because of an approaching deadline.