The money it costs to get someone to fix it. That person isn't free, unless this is their hobby. It's not about uptime, it's about the service existing at all.

The money it costs to get someone to fix it. That person isn't free, unless this is their hobby. It's not about uptime, it's about the service existing at all. Even if you are fine with an hour downtime per day; at the end of that hour, you'll still need to bring it back online. The "aaS" part is about taking that load off. The nines are a corollary. Concretely: a dedicated server leaves you with a lot of extra work. A packaged, managed service doesn't. E.g.: s3 for static files vs an nginx server on a VM. Even if they cost the same, s3 would still be a better option for git-scm.org.