It's only insanely expensive relative to the financing cost structure of traditional companies. If you view Tesla as a high growth tech startup, with an insanely cheap way to raise capital, you can say they are spending very little money to generate such high revenue growth rates, especially compared to say Uber.
Except not really, because number of Apple Watches sold in first month was in the millions whereas number of iPods sold was less than 100,000! I think OP is talking about rate of growth being like iPod, not absolute numbers https://www.lifewire.com/number-of-ipods-sold-all-time-19995...