Why Is a Trader Who Sells Options Typically Interested in a Decrease in Implied Volatility?

A trader who sells options (a short option position) is typically interested in a decrease in implied volatility (IV) because it will cause the option's premium to fall, allowing the trader to buy it back at a lower price for a profit. Since the seller is short Vega, a decrease in IV directly benefits their position.

They profit from the market's expectation of price movement subsiding.