In a purely competitive market, you're correct that all firms are price takers, meaning they cannot individually influence the market price. The market price is determined by the intersection of supply and demand. If a single firm in a purely competitive market lowers its price below the equilibrium market price, it would indeed lose revenue without necessarily increasing the quantity sold. This is because the lower price doesn't attract more customers since the product is identical to those offered by other firms, which are selling at the market price. As a result, the firm would earn less revenue per unit sold. Other firms in the market wouldn't need to lower their prices in response because the market price is already set at the equilibrium level where supply equals demand. Each firm in a perfectly competitive market is assumed to be operating at the lowest possible average total cost in the long run, so there's no incentive for them to change prices unless there's a change in their cost structure or market conditions