I've been managing servers for quite some time now. At home, on prem, in the cloud...
The more I learn, the more I believe cloud is the only competitive solution today, even for sensitive industries like banking or medical.
I honestly fail to see any good reason not to use the cloud anymore, at least for business. Cost-wise, security-wise, whatever-wise.
What's a good reason to stick to on-prem today for new projects? To be clear, this is not some troll question. I'm curious: am I missing something?
I'm the CTO of a moderately sized gaming community, Hypixel Minecraft, who operates about 700 rented dedicated machines to service 70k-100k concurrent players. We push about 4PB/mo in egress bandwidth, something along the lines of 32gbps 95th-percentile. The big cloud providers have repeatedly quoted us an order of magnitude more than our entire fleet's cost....JUST in bandwidth costs. Even if we bring our own ISPs and cross-connect to just use cloud's compute capacity, they still charge stupid high costs to egress to our carriers.
Even if bandwidth were completely free, at any timescale above 1-2 years purchasing your own hardware, LTO-ing, or even just renting will be cheaper.
Cloud is great if your workload is variable and erratic and you're unable to reasonably commit to year+ terms, or if your team is so small that you don't have the resources to manage infrastructure yourself, but at a team size of >10 your sysadmins running on bare metal will pay their own salaries in cloud savings.