There are a lot of good reasons to short the stock market right now. The best reason is the Austrian Business Cycle Theory. The Fed caused an artificial boom in the past and at some point it will go bust. It tried to go bust in 2008, but the Fed and the government pumped in trillions of dollars. The Fed did it by buying assets, particularly bad assets. The government is helping by passing stimulus bills and running trillion dollar deficits. They would not allow the previous bad investments to be cleansed out of the economy. They saw it as too painful.
The Fed created a lot of money out of thin air. Most of this money is being held by commercial banks as excess reserves. That is why we have not seen an explosion in prices. In the last 8 months or so, the Fed has had a more stable money policy, but of course all of the previous money that was created remains, mostly with the banks. At some point, we are either going to get a depression or massive price inflation. We may get both. I think the likelihood is that we'll start to get a depression and then the government and Fed will pump in more money which will eventually cause massive inflation. Eventually, there will be a choice between a severe depression and hyperinflation. Let's hope the Fed chooses the depression. I think it will.
In the short-term, a speculation to short the stock market may turn out to be a good play. It should only be a speculation though. This should be money that you can afford to lose. In addition, once it becomes more and more apparent that we are in another downturn, then be prepared to get out of your short positions. Once the Fed turns on the printing press or once the banks start to lend more, then prepare for high inflation. Stocks may go down in real terms, but in nominal terms (not adjusted for inflation), stocks could go significantly higher. At that point, I wouldn't speculate for or against stocks.