The simplest answer is they wanted to make money because they thought the stock was over valued. It is probably not due to EVs or Telsa specifically. Some people made a lot of money from it recently. From the article:
> The losses by short sellers are a stark contrast to a year ago, when shorts made a $15.9 billion profit on Tesla shares as the company’s stock lost 65% of the value.
But I'm also not sure where this idea of a whale short seller is coming from. With $13bn in losses almost entirely in 6 months, I would have to imagine there's just some riskier institutional investors.
Another way to look at it is they made it cheaper for people who are bullish on tesla to buy stock.