Hosting a Docker container is a full-time job? I have worked at several employers self-hosting their own instances without issues or a lot of effort. Many FOSS projects do, that definitely do not have a full-time guy for that. What are you talking about?
I imagine requirements and integrations may differ a lot. I have seen many incidents with a large instance.
if you accept the performance hit, it's great quality software though.
however, a fairly large company with 100-120 users (developers, devops engineers, QAs etc) and ~600 gitlab runners ran happily on a 8 core / 64gb virtual machine (hosted on a local vmware cluster).
so it is (was?) also fairly cheap.