This can not be overstated enough.
I own a Tesla Model S - purchased new and delivered in Dec 2017. It is - without a doubt - the most impressive car I have ever owned. Coming from a BMW and Audi background, I would purchase a Tesla again before even looking at the offerings from those other brands. It really is that impressive as a vehicle.
On the other hand - as an investment - its not something I could fathom touching. The burn rate of the company means that not only is profitability a long ways away, a dilution based equity offering is pretty much a forgone conclusion. Couple that with current valuations that have it near that of Ford/GM - established car producers making more cars in a month than TSLA will annually - and there is a recipe for a significant pullback even from these levels. The promise of the Model 3 leading the charge to mainstream adoption is nice in theory, but years away in practicality. Add in the enormous cost - and inevitible "production hell" - of the Model Y that is scheduled to begin at some point this year and its not unreasonable to think that consistent profitability for the company could be several years (and several rounds of equity offering) away.
Love the car. Absolutely love it. Not comfortable with the company for my portfolio.