[ak217]

Other comments have covered cases like departments having money left over in their quarterly budgets, or companies looking to spend in a particular quarter for earnings/tax deduction reasons, or reducing currency risk by hedging forex prices. But the biggest use by far that I've seen for this is government/public orgs that are prevented by outdated laws/auditing regulations/processes from using pay-as-you-go models. They are forced by their accounting department/government grant to treat infra expenses as capex and have zero budget to expense them as opex (this model assumes an on-prem physical plant for an IT department). Previously AWS had a way to get around part of that with reserved instances, this solution is more comprehensive.

[jrockway]

The pricing on reserved instances is so appealing over on-demand instances, though, that people are using it for more than just opex vs. capex accounting. You legitimately save money by buying in advance.