I think a company that saves $2B (meaning they were able and willing to spend even more before they had this idea) is more than able to have multiple competencies. Acquisition and vertical integration is how many companies became massive.
Of course it's a question of scale, but a lot of arguments I've seen usually come down to CapEx vs OpEx accounting which is silly because a dollar is a dollar.
CapEx vs OpEx isn't about raw numbers, it's about who can make the spending decisions and how quickly they can be made. At most companies getting a couple additional servers is a lot easier when you're running on public cloud vs running on-prem.
The general trend with cloud investment is that it makes utmost sense early in a startup or business expansion when time to market is the most important and uncertainty is high, but once the business stabalizes the assets move in house because of costs.
The cloud is powerful, but for long running businesses who can afford to invest in the competancy it's stupidly expensive. Hybrid cloud installations are ever more the norm, private clouds increasingly capable (PaaS, IaaS, SaaS), and toolsets like Kubernetes reshape how a lot of those legacy apps get looked at.
You can use financing arrangements to avoid dropping the money all at once -- for example: A service provider offers you a monthly subscription or "lease-to-own deal" where you sign a contract to buy the software or hardware in exchange for monthly payments to be made over a period of time; that could be indefinite, or you become the owner of the hardware after the end of its useful life. Or just go to a bank, and they will be happy to create a loan and write a check out to your vendor for the lump sum, and so you are only responsible for making required monthly payments of the interest plus any principal, etc, required by the contract.
So no... not necessarily... CapEx is not necessarily paid out all at once. So the accounting ought to be the same whether its a CapEx purchase under a Subscription Agreement/Loan, or if its an "OpEx" payment for 1 month of services.
in the case of computer equipment that needs replacement very 4-5 yrs (or less depending on compute and other reqs) you’re perpetually in a lease and this starts to become opex
Of course it's a question of scale, but a lot of arguments I've seen usually come down to CapEx vs OpEx accounting which is silly because a dollar is a dollar.