Some people see a glass of water as half full. Others see it as half empty. And then some see a glass of water like it's about to spill all over the table, and they're willing to bet that the disaster will happen. Those people tend to be short-sellers.
Short-sellers don't just think that a stock will go down. They think that at stock will decline so significantly that it's worth borrowing someone else's shares, selling the stock at the current price, and then buying the stock back at a much lower price before returning the shares to the lender.
In 2019, some short-sellers made a lot of money betting against marijuana stocks. Most pot stocks fell last year, with quite a few plunging in spectacular fashion. Many cannabis-related stocks still have a high percentage of outstanding shares sold short. But I think that short-sellers could be flat-out wrong about two of them.