Most people who buy and sell houses are not professional negotiators and are unable to look at the big picture (for example refusing to do a £100 boiler service to facilitate a £500K transaction).
A lot of sellers also need a certain amount of money to move to their next house. If the market will not deliver that, then they will not be able to move. Since it isn't costing them any money to have the place on the market, many will leave their property marketed for lengthy timescales rather than accept less.
I think you just have to understand that most people who sell houses have no experience in conducting transactions of this size. Which is why agents are often required to make them see sense.
As far as the OP is concerned, another poster had it right in the respect that if you marketed your house at half the current price you would almost certainly have a buyer. Somewhere then between this price and your current one is the price where it will sell for the maximum amount of money the market will bear. The question is how to discover that price. It can either be done by lowering the price gradually over time until someone shows interest. Or an alternative method is auction.
People want houses. There is a shortage. All the excuses of "its the red rug in the sitting room", "it's August", "the market is slow" etc are just that. Excuses for the fact that the house is overpriced in the current marketplace.
Ultimately a market is made by people who engage in transactions, not sit on the sidelines with overpriced properties. If you are getting no interest and you cannot afford for whatever reason to lower the price, you are probably going to have a long wait or not end up moving.
It's always possible though, even if unlikely, that someone may turn up at any time willing to pay an over inflated asking price.