When you factor in storage, backups, and all the little support costs, things start to get pricey. Just the db can go from 500gb to a tb. Then all of that data came from somewhere and needs to be stored at least for a while.
Never mind the load balancing. And then we need another server for a different client, and another, and a demo server, and test & staging environments. Ugh. I wish this were on-premmable. We could probably hire an employee for the amount we could save. He'd probably be pulling his hair out supporting it tho. lol
My little on-prem HP dev server's got hundred gigs of ram and 8tb of fast storage. We run a bunch of VMs on there. We paid a couple of thousand dollars for it. And I don't even want to think of what it would cost to ship those VMs to the cloud. Nevermind just how poorly they would perform.