Technology

The actual definition of shorting is that you borrow shares, sell them, buy back when cheaper, then return. This has infinite downside because it could go up and you don't know how much and you're on the hook for the shares borrowed.

The thing most people on wallstreetbets and the like do, is buy "put" options. It's a stock option contract that gives you the option to sell a certain amount of stock for a certain price before a certain date.

Example: Company's share price is 1000$. You believe it will fall to 500$ because you think it's super overvalued. You buy a bunch of put options for a date after what you think is correct, for say 900$. Since the price is lower than the current price, the options are cheap. Once the stock price actually drops below 900$, it the options go up in value. You can now just sell the options instead of actually exercising them (which would imply buying cheap stock and selling it for the more expensive price in your option contract).

Options can go up or down in value significantly more than the underlying stock. Very easy to lose all the gambled money, but if you get lucky, you can multiply your money. But as they say, the house always wins. And we're not the house.