Elon Musk is the richest person in the world with a reported net worth of $359.4 billion[1]. Why does he want to steal our tax dollars? What indication is there that further self-enrichment is his goal?
It's not clear that this isn't the more cost-effective solution. Without diving into the pricing of each component shown, I suspect there may be some cost optimizations to make (for one example, I had a hard time discerning from the write-up what the EC2 instance was doing...something related to more weather data collection I think?) but this is approximately "cloud-native" in approach, and the way to minimize costs in the cloud is to design your application to be cloud-native and use managed services and provider-specific capabilities where they make sense (and also tend to offer very low/free per-use pricing). Does that increase vendor lock-in? Definitely. It's a trade-off that needs to be considered for each application. Using the cloud to run a bunch of static VMs is an anti-pattern and a big factor in driving costs through the roof. (If you need a single server, a VPS is a very good approach.)
The architecture is complex from the standpoint of having a lot of icons and arrows, but if it was running on a single server would it be _that_ much less complex? At this level of architectural diagram you probably condense most of these service icons down to one or two icons. But drill down further and you still have storage, cron jobs, an API endpoint with throttling/quota logic, CDN, a shared filesystem, the need to access the S3 buckets with weather data that AWS is providing from its Open Data Registry, plus (ideally) fine-grained permissions to lock everything down. Could you run all of this on a single server in a VPS? Yes! Could you run it on a vendor-agnostic K8s cluster? Yes! Would those options automatically be less expensive? Not necessarily.
[1] https://www.forbes.com/profile/elon-musk/