I'm not an expert on the financial market and do not provide advice on where to invest money. Some people however are going short on Tesla's stock for quite some time now. Even though, in my humble opinion, Tesla is doing great and will prove to be a huge success. There is only one logical reasoning behind going short on Tesla and betting against their success; either way you'll always win. If Tesla is going to be a huge success, we all have a better place to live in. If Tesla isnot going to make it, you will at least have the money to pay for more overpriced fuel.
Why Tesla will need more loans to make it through 2013:http://www.autoblog.com/2012/12/28/why-tesla-will-need-more-loans-to-make-it-through-2013/
It's fun to bet against Elon Musk and Tesla – that's the best reason we can find for so many people doing it even though the man, his company and his cars are still here and still very popular.
Personally, I'd go for Tesla's success, as a 'have the cake and eat it'-kind of thing.