Kubernetes is often referred to as Container as a Service (CaaS) and is placed as an abstraction layer between the cloud service model Infrastructure and Platform as a Service (IaaS and PaaS). While from a developer perspective it focusses to appear rather as a PaaS model, from a financial perspective the costs incur from the IaaS model. The costs incur from the runtime of the assigned virtual machines - whether they are well utilized or not - as opposed to paying for the runtime of the containers. This is one of many adoption insights in terms of "hidden costs". In this talk Matthias and Thorsten describe their experience about those costs based on the experience of adopting CaaS in several client scenarios. In most cases it was set-up to achieve a "PaaS-like" self-service developer experience. This covers 5+ years of lesson's learned in on- and off-prem setups, GitOps, security, automation, application deployment, legacy integration, observability and skill enablement.