I know it’s the big lock in boogeyman on HN, but learn about at least one cloud service - not just how to host a few VMs. Learn about their hosted, managed versions of open source software, managed network infrastructure (load balancers, autoscaling, etc.) and even proprietary services.

You can’t come up with a real scalable fault tolerant solution if you don’t understand the underlying infrastructure and cloud hosting is the fastest way to do it.