[badminton1]

I think you are not counting: QA, user experience, DevOps, technical writing, security auditing, user training, integration support...

What happens if the system collecting all of your data has vulnerability? suddenly all of your apps and data are owned.

What if it's inefficient? then you have DDoSed yourself.

Non-functional requirements cannot be solved with a functional requirement mindset.

What if you are losing data? what if you aggregate it incorrectly? what if data is ingested in the wrong order? ... you get the idea.

It's not a 3 people problem. When you take on a hard problem like this you have 10 different things to cover and you need to pick all of them.

[brango]

Having built something like this myself the components you actually need to write are so small and simple the scope for security issues is minimal. All the infra scales automatically.

Also, this post only addresses data flowing in one direction into BQ. Presumably they're then using something like Tableau or the Google/AWS offerings to build dashboards based on this data. There aren't many places for bugs to hide unless the BQ perms are wide open.