It's not bonkers at all. Musk's strategy from the beginning has been hype-driven. This gives him low cost of marketing and low cost of capital. But the downside is that the stock will appear overvalued to observers who don't buy the hype.

This would be true even if things were going well and Musk were going from strength to strength. But Tesla has had a whole raft of problems, many of them self-inflicted. This is catnip to shorts.

Further, part of Musk's strategy has been to bank on the genius-founder stereotype. It has clearly paid off as well; I'd bet that that there's an order-of-magnitude difference between the percentage of people who can name Tesla's CEO and that of any other car company. But again, it's risky; if Musk quit or were forced out, confidence in the company would collapse. And he has made a number of unforced errors; no other car company CEO is in dutch with the SEC. This kind of risk is also hugely appealing to shorts.

It's also worth noting that the shorts were right. Tesla's managed to lose half its value from the peak, and it's still down something like 30%. Some of them have surely made a ton of money.