There are many reasons why Tesla may not do well. Most of them sound pretty far-fetched at this point. My biggest worry right now is that the stock is overpriced and that Tesla won't be able to increase production and sales as much as they have forecast. Other possibilities:
-Elon Musk dies in an accident. New CEO is unable to follow up on disruptive vision (Tim Cook, I'm looking at you).
-Temporary setback for Tesla (or global stock market crash) thrashes Tesla's stock market value. Goldman Sachs gives Elon Musk a margin call, followed by a hostile takeover by established auto industry. New majority owner slowly butchers the company by purposeful incompetence.
-A massive US recession which starts right now and kills Tesla's luxury car sales in the crucial ~5-year period until G3 launch. Tesla runs out of cash and is unable to raise more, going bankrupt and getting sold for parts.
-Global battery development stalls, and it turns out it will be impossible to create a cheap car with >200 mile range. Or it becomes impossible to create any electric car with considerably greater range than 200 miles. Similar worry for quick charging.
-The premise of electric cars was erroneous. In spite of what we've seen already, electric cars will never be a disruptive force in the auto industry. They will remain a niche product, inferior to gasoline cars.
-Multiple car companies realize that electric cars are about to become a disruptive threat, and are able to leverage advances in battery technology and scale production faster than Tesla. Tesla is still successful, but only gets a small pie of the global electric car market. Tesla essentially remains a luxury carmaker. Stock price falls to $40, a decent P/E multiple in this new world.
-Global event that would leave you ****ed regardless. E.g. a large, global war which derails Tesla's supply chain and makes everyone think about other things than buying a car. Tesla runs out of cash and goes bankrupt.
-Black Swan event: An "unknown unknown" that somehow derails Tesla's plans.
None of these scenarios seem very plausible to me. I would love if someone could come up with better (worse) ideas. The thing is, and this is also what you can see from this thread, at the moment it seems exceedingly likely that Tesla will succeed. It becomes harder and harder to envision a scenario where Tesla will be unable to scale up and become a major carmaker. This, in addition to the disruptive potential of electric cars, is an explosive combination. Maybe most people won't want to drive a gasoline car in 15 years? The first-mover advantage would mean getting way beyond a $150 share price if this scenario unfolds. But I still think that $150 seems like a decent risk-adjusted stock price for now. Tesla is still a speculative growth stock.
I think that this is the time to be cautious. When no one can see what could possibly go wrong is the time that stuff usually starts going wrong.