Even if you have a full-time role for continuously auditing the infrastructure (which I would say is the responsibility of either a security officer or a devops engineer), you still didn't show how that needs a 15-person team, and an otherwise-untouched infrastructure should just keep on working (barring sabotage), unless someone really messed something up.
If CI builds or deployments keep randomly failing at your place, that's not an inescapable reality, that's just a symptom of bad software development practices.