I don't think they're arguing anything.
The parent wondered:
> It would be interesting to see what the corresponding figures are like for on-prem
They replied. Not everything is an argument.
Also, they didn't say anything about fixed capacity - they're likely just talking about 10Y deprecation which is a very common accounting thing to use - and "For everyone else the cloud is cheaper" is definitely not true. It depends on workload and architecture. If you're in the business of selling infrastructure, for example, using the cloud will eat most of your margins (this is not to say that it's not done, but usually there's some caveats, e.g. maybe you will get some cheap VMs provisioned and do your own fleet management ontop instead of building everything on top of say, firebase or dynamodb).