Why is SNS so expensive?

Could you elaborate on why SNS, or social networking services, tend to be so expensive? Are there specific factors that drive up the costs, such as the need for extensive server infrastructure, high-end technology, or perhaps intense competition in the market? Additionally, do the monetization strategies employed by these platforms, such as targeted advertising and premium services, contribute significantly to their overall expenses? Understanding these dynamics would provide valuable insights into the economics of social networking and its potential implications for users and investors alike.