Your usage seems to be in the "large" customer category where provisioned capacity is a better deal. Algolia does have volume discounts if you talk to them, but yes the other alternatives might be a better fit.
You're missing the point. Their scale (in number of records and queries) is a better fit for provisioned capacity than pay-as-you-go in the context of billing.
The exact small/large label doesn't matter, nor does the requests-per-second.
Would you mind sharing your thought process to get from `daily_users` to `reqs_per_sec`? I'm playing with some estimations of `concurrent_users` for a basic website, and I'd be quite interested in the breakdown.