

Total guess, but probably $100-150/mo or so to rent 1U (and redundant power), and probably an installation charge (and a charge every time they need to touch the hardware for any reason). There may be extra charges for the uplink.
Unless you have a need for that specific hardware to be there, it would probably be cheaper (and more maintainable) to go rent a virtual server somewhere.

Those senior engineers became skilled by starting out as entry-level engineers who didn’t know all that stuff, but learned from the senior engineers before them (and by writing a lot of bugs that hopefully got caught by code reviews.) Now, companies are using AI as an excuse not to hire entry-level people.
15 years from now, we will find there are no mid-level people to promote, because they never got their entry-level job and are now waiting tables.