Ten million users [1] averaging maybe averaging 40 or so interactions per year (filling out an expense report isn't a common task for a lot of those users)? Napkin math of 1.2 qps. Even if you 10x that for backing workflows, and double it because users are more active than expencted, that's still only 30qps.
Given the time, effort and hard dollar expense they put into development of BedrockDB - I have to imagine they do more than 1 QPS.
Why else would they benchmark to show they can achieve 4,000,000 QPS if all they need is 1 QPS?
Sunk cost fallacy?
While I think the figures might be a little conservative (or might work for the mean, but not the peak) it is a little odd to imagine why an expenses app would need a database that syncronises via a private blockchain to track expenses. It would be interesting to understand the rationale.