Very simple: you need to get higher level of service, instead of paying for servers you need to pay for up-time. It's what PaaS, managed service or serverless does : manage server for you, at scale. To have something online you need:
- servers
- VM/OS management
- Scalability system
- monitoring (hardware, OS, applicative & functional)
- action on monitoring and escalation management
- update every weeks
- observability