Earlier quoted context omitted.
This is not really true. Not "once you reach a certain size", but once you move off the lowest-tier starter hardware, cloud quickly becomes much more expensive than owning hardware, and security solutions continue to depend on the individual administrators (most backups do too). Cloud's biggest benefit is really convenience, because you don't need to go to the datacenter and put in another hard drive yourself when yo…
For "convenience" substitute "having the technical sophistication to manage it properly". How many companies know enough to hire and retain top-notch people to run a datacenter and keep upgrading it?
Chasing the cloud has cost companies a massive amount of money. I'm familiar with companies that would've saved nearly a million bucks a year by staying on bare metal/in-rack hypervisor. They weren't forced into the cloud by a shortage of people who could perform hardware maintenance, they went because it was the hip thing to do.