Just because you can't do it doesn't make it impossible. A small team of 4-5 good ops people can scale a network of many thousand nodes, petabytes of storage, and terabits of network throughput.

Tech stuff isn't hard. The biggest problem is the lack of capacity planning and project communication in tech today. Nimble startup is a euphemism for pure anarchy and chaos. No one wants to plan anything any more.

The same infra could be managed by a single guy if it were in the cloud.

No, because that "guy" would want a vacation and would suddenly become the most important person in the company. You're running teams of people, not cogs. Once you realize that, you'll also realize that cloud services are like 5-6x the total cost.

Cloud services are not efficient or cheap, they're convenient for the unprepared and haphazard management style that VC's love.

You should review the difference between CapEx and OpEx, and specifically focus on why companies might prefer to pay “5-6x the total cost” when that cost comes in the form of OpEx.

You may still disagree in the end, but you should come to the conclusion that it is not categorically stupid for some companies to choose to pay much more over time so that they can pay a lot less right now.

Only by abstracting away hundreds of teams that manage the actual hardware.