Elon Musk wants to challenge the notions that Tesla can only thrive with government subsidies and that he's only in the business for "making money."

The CEO took to Twitter early Friday to explain why he and other Silicon Valley engineers started Tesla in the first place, following increasing criticism earlier in the week from investors who are shorting the stock.

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Musk is referencing the saga surrounding the recall by General Motors of the electric EV1 car in California in the early 2000s as documented in the popular movie "Who Killed the Electric Car?" Tesla was founded in 2003. The motivation behind its start is not detailed on the company's website.

On Thursday, Musk tweeted out an Investopedia article saying Tesla is the most shorted company in the U.S. equity market. The article cited data from financial analytics firm S3 Partners, which said the short interest in Tesla totals about $10.4 billion.

Despite the threat from short-sellers, Tesla shares hit an all-time high Thursday as the company moves toward starting production on the Model 3 sedan. The stock is up more than 73 percent since the beginning of 2017, and shares have climbed more than 61 percent over the past 12 months.

Tesla's stock closed at $370 per share on Thursday, up about 3 percent for the day.

Read: Elon Musk: People betting against Tesla 'want us to die so bad they can taste it'

—CNBC's Robert Ferris contributed to this report.