Is TSLA borrowing too much?

They have no choice.
Its a huge house of cards. The apple WILL lose its shine...the run in the stock has been financed on the backs of put buyers and shorts. Pure and simple.

 

What kind of question is this when interest rates are negative?

 

Well, they're not exactly negative, and if one has a working business model that is actually growing revenues and earnings, you certainly have a valid point. Thats why we are at all time highs. That being said... key here is... "working business model that is actually growing revenues and earnings".

 

https://seekingalpha.com/article/4097058-thoughts-teslas-latest-bond-offering

 

Note the top card.

 

5% for non-securitized junk paper?....no thanks.

 

Boeing pays a 5.68% divy.
Hmmmm. Which one should I park my money in?

 

I believe they need to invest in expensive equipment so like van has pointed out they have no choice. Air boeing and other industries where they require heavy initial investment, it's common for them to finance with debts.