Kidding aside, running a bare metal server you own or rent is always cheaper, assuming you cannot save money by turning things on and off and know you capacity needs. Sure HN grows but not nearly as fast as FB, Twitter, etc. the service is big enough where it would require expensive virtual servers. This is the best case scenario for a physical hardware box run by people who are familiar with such things.
Kidding aside, running a bare metal server you own or rent is always cheaper, assuming you cannot save money by turning things on and off and know you capacity needs. Sure HN grows but not nearly as fast as FB, Twitter, etc. the service is big enough where it would require expensive virtual servers. This is the best case scenario for a physical hardware box run by people who are familiar with such things.