Even an hour a month of lost dev time would make it worth it.
Your not just saving developer downtime. Remember that non incident a few months ago? Could be a security issue too.
What certainly has wasted a horrible amount of my time in recent years is working around build systems and package managers that are so badly designed that not only do they have a dependency on some online repository in the first instance, they also make it difficult or impossible to download and cache those dependencies in a supported way so that you can have 100% reproducible builds with nothing but locally hosted resources. Surely this is just about the most basic requirement for a robust software development process?
I self host my gitlab and when there's an update it goes down for several minutes (well actually I don't know if it's unusable, haven't tried, but with the backup and the updates, it's long)
I'm the only one working on it, so that's not a problem for me.
Still, it takes time.