The link failed to explain the dangers of shorting. You can get caught in a short squeeze:
A situation in which the price of the stock rises and investors who sold short rush to buy it to cover their short position and cut their losses. As the price of the stock increases, more short sellers feel compelled to cover their positions.
You can lose many times your initial investment. Many times.
The risk of shorting is that you can be early in assessing the loss of a company. The markets may take many more months to price in the loss that will eventually take place. Rallies can happen before the big loss.
Small players can get run over by the pros in a short squeeze. Shorting is for the pros!