Self hosting is the best solution for our team. At least we can blame ourselves if something is down...
Our self hosted Gitlab instance needed a lot of hand holding over the years, occasional memory upgrades and involved much more work than initially anticipated. Also keep in mind that you need to spend time to keep the thing up to date and get latest features, which there have been quite a few good ones added over the years.
That attitude isn't really conducive to custom software development, but Gitlab has many other purposes.
Without numbers, I don't see how you can make any decent conclusion at all.
Is that all you have seen? I have seen many self hosted services fail in our company and the answer is almost rarely any of these simple things but complex things like data loss, data corruption, random restarts, network partition, configuration sync issues etc. That is why companies pay other companies for critical things like gitlab even when self hosting.