Why are serums so expensive?

Can you explain why serums tend to be quite pricey compared to other skincare products? Is it due to the high-quality ingredients used, the intricate production process, or perhaps the exclusivity and branding associated with them? Do serums offer unique benefits that justify their steeper price tags, or are they merely marketed as premium products? I'm curious to understand the reasoning behind the cost of serums and if there are any alternatives that provide similar results but at a more affordable price point.