I'd really like to know where their costs are coming from, $400m/yr seems absolutely wild. I work for a large org who has 90-95% of stuff in cloud infra and we don't spend even close to this.
Thousands of beefy EC2 instances, petabytes of warm-to-hot S3 objects, chunky RDS instances and a large data warehouse add up pretty quick.
It's important to note that these negotiated prices are way, way less than the sticker price. It's a win-win.
In short: it does not matter for a company that does not even have a profit and probably won‘t reach break-even soon. It‘s a waste of time to cut cloud-computing cost at that stage of the company.