- access to capital is getting tight
- Tesla has less ability than Amazon to spin the story that "we can turn down our reinvestment at any time to turn on profits"
Amazon nearly went bankrupt after the dotcom bubble era. They were drowning in particularly bad debt and red ink for years. After the dotcom bubble their financing abilities almost entirely dried up, the stock collapsed by ~93% or so. It was almost universally expected that they would not survive, culminating with the infamous Barron's Amazon.bomb story and a parade of stories thereafter. For the next three or so years after that story, bankruptcy was the anticipated end by the press and analysts. Tesla today, when you look at how they're being discussed by the press + analysts, and their financials, looks similar to Amazon's general condition back then (Tesla's growth is both faster and its red ink is greater, than Amazon was back then).
For reference, Amazon had $1.6b in sales for 1999 with a $719m loss, and a $30b plus market cap at the peak of the dotcom bubble. Tesla will probably hit around $17-$18 billion in sales for 2018. If the market lets out - the supportive environment broadly - you'll see Tesla's stock crater unless their burn rate is very sharply reduced. They'll suffer the same financing concerns that pushed Amazon's stock down to $5.51 / share in 2001.
Additionally, what about the comparison between capital climates both these companies have to go through?
Amazon taking on debt had their interest obligations reducing. Interest rates started out at 5% in 1999 and then saw going as low as 1% in 2002. Increasing to 5.25 before going back to 1% again.
In comparison, Tesla has been operating under record low rates of less than 1%. The only way from here is uphill.
Source for rates:
https://www.thebalance.com/fed-funds-rate-history-highs-lows...
Tesla on the other hand is into manufacturing. It will see some of it's costs scale as well even when it is doing better.