For some reason, car owners in Qatar refuse to acknowledge the existance of depreciation. If it was just a few car owners then no, they would not get the crazy prices they ask for. Unfortunately, it is all car owners and so this artificially inflates the entire market and so buyers have no choice but to pay.
If you're lucky you may find someone going back to their home country and desperate to sell, but as the population is still growing at a huge rate the demand for cars will remain high.