You will find that your home is better marketed, that you don't have to rely on the luck of a drive by, that you save a great deal of money, and that you are linked in with thousands of realtors who essentially end up working for you if you are on the MLS.
Your real estate agent can provide you access to a wider range of listings than you would be able to find on your own.
If one pays to steep a price for the property, their profits will be damaged until they either sell the property or pay it off.