I worked in operations for a large company that had their own 50,000 sq ft data center with 2000 physical servers, uncountable virtual servers, backup tape robots, etc... Their cooling bill would like to disagree with your assessment about scaling. I was unpacking new servers regularly because, when you own you own servers, not only do you have to buy them, but you have to house them (so much rented space), run them, fix them, cool them, and replace them.

Don't get me wrong, I've also seen the AWS bill for another large company I worked for and that was staggering. But, we were a smaller tech team and didn't require a separate ops group specifically to maintain the physical servers.