Entirely depends on use case. If you "just" need a lot - a lot of storage, bandwidth, CPU power - going on prem is way cheaper when you get up to "few racks of servers".
If you complicated your architecture enough - and the cloud makes it oh so easy to make rube goldberg architecture - keeping many different services running or even developing in-house can take a lot.
And it's not like cloud costs you zero in ops work either, just need different set of skills.
But it is not like on-prem stagnated - there is plenty automation in that space too. Our team of 3 manages 7 racks of servers and few dozen projects on them (anything from "very legacy" to 30+ node k8s cluster and ceph storage with it) and the hardware management still isn't majority of our work
If you complicated your architecture enough - and the cloud makes it oh so easy to make rube goldberg architecture - keeping many different services running or even developing in-house can take a lot.
And it's not like cloud costs you zero in ops work either, just need different set of skills.
But it is not like on-prem stagnated - there is plenty automation in that space too. Our team of 3 manages 7 racks of servers and few dozen projects on them (anything from "very legacy" to 30+ node k8s cluster and ceph storage with it) and the hardware management still isn't majority of our work