Running gitlab yourself is just too expensive. Too many docs to read, hard to understand, just too much software in general (just compressed deb package alone is 1GiB in size), hard to backup, hard to debug issues, would require a new separate much more expensive VM, etc. It does weird shit during installation, like contacting letsencrypt and trying to fetch a certificate and failing if the machine is IPv6 only, etc. etc. Recovering from that is not documented anywhere. Too many moving parts. Just sort of blergh for people who like simple solutions.
It doesn't sound like a 1-2hr/year self support software.