> If we can't bill a customer for it, and it's not scaling regularly, then it shouldn't be in the public cloud. That's my take, anyway. It sucks the wind from the sails of folks gung-ho on the "fringe benefits" of public cloud spend (box seats, junkets, conference tickets, etc...), but the finance teams tend to love such clear numbers.
I agree, but.
For one, it's not just the machines themselves. You also need to budget in power, cooling, space, the cost of providing redundant connectivity and side gear (e.g. routers, firewalls, UPS).
Then, you need a second site, no matter what. At least for backups, ideally as a full failover. Either your second site is some sort of cloud, which can be a PITA to set up without introducing security risks, or a second physical site, which means double the expenses.
If you're a publicly listed company, or live in jurisdictions like Europe, or you want to have cybersecurity insurance, you have data retention, GDPR, SOX and a whole bunch of other compliance to worry about as well. Sure, you can do that on-prem, but you'll have a much harder time explaining to auditors how your system works when it's a bunch of on-prem stuff vs. "here's our AWS Backup plans covering all servers and other data sources, here is the immutability stuff, here are plans how we prevent backup expiry aka legal hold".
Then, all of that needs to be maintained, which means additional staff on payroll, if you own the stuff outright your finance team will whine about depreciation and capex, and you need to have vendors on support contracts just to get firmware updates and timely exchanges for hardware under warranty.
Long story short, as much as I prefer on-prem hardware vs the cloud, particularly given current political tensions - unless you are a 200+ employee shop, the overhead associated with on-prem infrastructure isn't worth it.