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If you have an application where the performance and growth patterns are well known, cloud isn't a choice made for lowest cost. It may be best value for different reasons.

I've done ROI studies for several applications like that, and usually cloud has a higher total cost unless there are specific availability requirements or you don't have a facility that can meet a 99.9 SLA.

The key assumption is that you know a lot about the app and it's in a operating mode. If you're in a hyper growth mode, have fluctuating or seasonal demand, or you have no capital funds, cloud is a no brainer

So there's 3 things you can use the cloud for:

1) your company is totally fucked for IT management, and the cloud beats local because of incompetence (this is very common). And you're unwilling or unable to fix this. Or "your company doesn't focus on IT and never will" in MBA speak.

2) wildly swinging resource loads, where the peak capacity is only needed for 1-5% of time at most.

3) you expect to have vastly increasing resource requirements in a short time, and you're willing to pay a 5x-20x premium over dedi/colo to achieve that