Apple’s Macintosh made waves with its cheeky hello world demo: “Never trust a computer you can’t lift” (…and defenestrate).
Similarly, with an IBM big iron box, if something goes wrong, I sure hope the 6-figure support contract gets it fixed - probably within a few hours if you’re in Manhattan or the SF Bay, but what about elsewhere? Whereas with commodity HP/Dell/Supermicro pizzaboxes in a HA configuration I don’t need to worry about needing a same-day fix for hardware issues - I could put things off for months, even - and probably do it myself and spend the support contract money on a Plaid Model S and have money left-over for a Mac Pro with XDR display (with the cool stand!).
I know IBM’s srsbsns machines have their own redundancies - including being able to hot-swap literally everything, it still feels like open alternatives are overall better in the long-run.
We just paid just under $50k per server for on-prem physical servers that have 144 cores per server and 1.5 TB of RAM each.
For 12 of them it would be less than $600k and you'd get a total of 1,728 cores and 18 TB of RAM to compare against the mainframe's 30 cores and 2 TB of RAM for over 4x the cost!