The point was about redundancy / geo spread / HA. It’s significantly more difficult to operate two physical sites than one. You can only be in one place at a time.

If you want true reliability, you need redundant physical locations, power, networking. That’s extremely easy to achieve on cloud providers.

You can just rent the rack space in datacenter and have that covered. It's still much cheaper than running that in cloud.

It doesn't make sense if you only have few servers, but if you are renting equivalent of multiple racks of servers from cloud and run them for most of the day, on-prem is staggeringly cheaper.

We have few racks and we do "move to cloud" calculation every few years and without fail they come up at least 3x the cost.

And before the "but you need to do more work" whining I hear from people that never did that - it's not much more than navigating forest of cloud APIs and dealing with random blackbox issues in cloud that you can't really debug, just go around it.

How much does your single site go down?

On cloud it's out of your control when an AZ goes down. When it's your server you can do things to increase reliability. Most colos have redundant power feeds and internet. On prem that's a bit harder, but you can buy a UPS.

If your head office is hit by a meteor your business is over. Don't need to prepare for that.

You don't need full "cloud" providers for that, colocation is a thing.