Very interesting question.
A couple of thoughts for you to consider:
1. Why would a Realtor take a listing, knowing that they had a 50/50 chance of actually selling the property?
2. When I take a listing I am investing a great deal of time, effort, and resources to market a property. To put this in terms that might help you understand, how would you like to invest $1,000 into a project with the odds 50/.50 that you will not only recoup your investment, nor make a profit?
3. If your Realtor has an excellent marketing plan (just for the record, not all Realtors are equal-only about 35% of Realtors are full-time) then they should be able to help you understand why they do what they do and how it will help you sell your property for top dollar.
4. A minority of properties are marketed and priced correctly. I am going to use stats from my MLS to make my point: Listings that sell within 30 days sell closest to asking price. For the month of January listings sold for 100.99% of asking price. 36% of the listings that sold. That means that the rest, 64%, sold for less than asking price. At 120 days that is 93.6% of asking....and that is AFTER price reductions.
So you need a Realtor with a marketing plan that you can understand, and one that values getting your home sold for the highest price, which means all of the marketing must hit at the same time. This requires a plan, organized execution, and follow up. Skills that only a very small amount of Realtor possess.
90% of the time listings sell to buys brought by other Realtors. Realtors who know price, value, and have buyers that are qualified.