I work for an ISP and we are trying to write another success story ;) As an ISP, we have tons of constraints in terms of infrastructure. We're not allowed to use any public cloud services. At the same time, the in-house infrastructure is either too limited, or managed via spreadsheets by a bunch of dysfunctional teams.
For my team, Kubernetes has been truly a life saver when it comes to deploying applications. We're still working on making our cluster production-ready, but we're getting there very fast. Some people are already queuing up to get to deploy their applications on Kubernetes :D
What I especially love about Kubernetes is how solid the different concepts are and how they make you think differently about (distributed) systems.
It sure takes a lot of time to truly grasp it, and even more so to be confident managing and deploying it as Ops / SRE. But once you get it, it starts to feel like second nature.
Plus the benefits, in almost any possible way, are huge.