And it's hard to say what class the Model S fits in. I don't think 7 or S is right, despite the price point. Those are both full-size luxury sedans, and while the Model S may be a full-size sedan, it's hardly luxury. Its interior is closer to a 3-series or E-class than the top-of-the range luxobarges. That's not a knock on build quality, just the reality of battery power currently being much more expensive than ICE. You've got to shave cost somewhere, and Tesla shaved it off luxury.
Buying TSLA right now is making a big bet on the Model 3. If Tesla comes out with a popular car (likely) and can make enough of them to turn a profit (little more skeptical on that one), it may end up justifying valuations. I wouldn't put my money on it, but I'm not surprised other people do.
http://cleantechnica.com/2016/01/15/1-large-luxury-car-in-us...
"As we all know, Tesla doesn’t report sales/deliveries by country. However, various outlets estimate Tesla sales using a variety of methods. EV Obsession estimated 26,566 Tesla Model S sales in the US in 2015. Rob notes that the lowest estimate was 24,200. In either case, the Model S outsold the Mercedes S-Class, the BMW 7-Series, the BMW 6-Series, the Audi A7, the Audi A8, the Porsche Panamera, and every other car in this class."