The other big issue people usually don't mention or consider when discussing dedicated hardware is that not only will it take longer to add capacity, but it is

The other big issue people usually don't mention or consider when discussing dedicated hardware is that not only will it take longer to add capacity, but it is also a risk every time you add servers you risk the entire network that server is being added too. Unlike a cloud environment, adding servers to a dedicated environment is not necessarily going to be as well practiced - so errors are more likely... These types of errors are pretty bad too e.g. All servers offline kind of bad. We had this happen two very bad days followed and now I can only recommend aws with reserved instances and multiple regions.