The 5% number isn't an ironclad rule, it's an arbitrary example. There's nothing bad that suddenly happens if your 5% position later becomes larger.
If you short a company valued at $50B, with 5% of your portfolio, it would have to become a trillion dollar company before you go insolvent.
If that's still too scary for you, you can short it with 1% of your portfolio. Now the company needs to become a $5T company, before you go insolvent.
If you honestly think that Tesla will surge into a $5T company, before crashing back down to <<$50B, then you're the one living in a reality distortion field.
If you claim to be extremely confident about Tesla's stock crashing, but aren't willing to take even a 1% short position, then your actions don't match up to your words.
Note as well that the long term may never come. A company can be acquired at an "irrational" price before reality imposes itself.
Did you short Monsanto in 2015 because you expected Roundup lawsuits to hit the stock? Well, you were kind of right but that's Bayer's problem now. Monsanto (the stock MON) is no more and you position was closed at a loss.
If you short a company valued at $50B, with 5% of your portfolio, it would have to become a trillion dollar company before you go insolvent.
If that's still too scary for you, you can short it with 1% of your portfolio. Now the company needs to become a $5T company, before you go insolvent.
If you honestly think that Tesla will surge into a $5T company, before crashing back down to <<$50B, then you're the one living in a reality distortion field.
If you claim to be extremely confident about Tesla's stock crashing, but aren't willing to take even a 1% short position, then your actions don't match up to your words.