On S3? $0.023 per GB. The data is most likely stored between RAM and SSDs these days. Aka on microchips made up of silicon. Which is sand. Which is all of, like, $50 for a literal ton of it. If you want to ask someone what about their mark-up, look at TSMC, their raw material is practically free, and they deign to charge exorbitant amounts of money for melting it in a (very, very) special way.

But you're not paying for storage costs, you're paying for the salaries of everyone involved with making the product, as well as the hosting costs, and some amount of profit to do with as they please.

Which is fairly pretty central to how capitalism works!

My earlier point is that they have enterprise plans, for those that don't want to pay per-user fees, but, uh, they're enterprise priced.