How has gitlab "continued to improve"? They are getting worse. Do you have statistics on their uptime or their performance? Because in my own experience, gitlab.com is going from bad to worse. Their API increasingly returns 503s and timeouts. Their UI is increasingly returning a stale state. One pushes a branch and they say it doesn't exist. One does a git pull and it takes so long one is used to going off and putting the bloody kettle on. They don't know what they're doing. I don't have the time or inclination is to collect demonstrative evidence, but it'll take something to say they are "continuing to improve"!
You and GP are talking about different things. As you say, Gitlab.com has been deteriorating and has continual performance issues, however Gitlab Core (the OSS project) has made big strides in the last year in adding features like excellent CI/CD integration, issue boards, merge request templates, web based IDE for quick edits, etc. For teams of people working together, these tools are really useful and important, less so for big community or solo projects.
Unlike Github, you can host Gitlab on your own server, to get whatever performance you're willing to pay for.
It's not fear. It's experience. Having to keep an extra OS and software patched and up-to-date (often times different to the rest of your SoE because it's different software) and keep it safe from real-world threats takes a lot of time and context-switching to do well.
Hosting anything well takes up a lot more effort than the $100+/month we pay to GitHub and even the $7/month I pay personally.
