short selling

Is the poor old short seller the rreason for the market downturn thats debatable,you could use the same arguement for the buyers who paid blue sky prices and drove up shares well above their intrinsic value in a frenzy of greed paying little heed to the true state of these companies.If someone judges the market is well overpriced why shouldnt he be able to attempt to take advantage of his judgement ,he is still taking a risk when he shortsells and can lose a great deal of money if he is wrong.