Spot on @Jonathan Cutting!
I was witness to one IT group blowing through their full-year Cloud budget within one quarter. OUCH!
What some don't realize is the infrastructure typically replaced with CapEx dollars is now being replaced with Cloud instances using OpEx dollars. If the retiring infrastructure assets are not decommissioned and remaining depreciation, if any, cleared off, the affect onto OpEx can get very crazy!
It's very easy to spin up Cloud without proper governance and structure that it gets out of hand VERY quick. Another gotcha is ensuring proper attribution of the Cloud instances, RIs, accounts, and more to enable relationships to applications, environments, cost centers, etc.
If your on-prem shop has a lot of the infrastructure mapped to "stuff" (eg apps et al) and making a mad dash to Cloud, you might find yourself in for a VERY rude awakening to learn Cloud instances were spun up without similar mappings. UGH!
If Cloud was spun up for days (plural) without any mappings and clocking in at a lot of cost per day, IT leaders will find themselves very challenged to identify which Cloud instances can be re-balanced, turned off at set times, supplemented with an RI purchase strategy, etc without affecting service to clients or even which clients to partner with to resolve.
Cloud has tremendous benefit, but great reward only comes with great responsibility.