That's generally the economic case put out in cloud planning: a startup or expansion does great in the cloud with quick time to market, but once that business has matured and the risk is gone the assets move in-house because it's wildly cheaper.

And something that seemingly everyone forgets: it's not black and white... you can have some things in the cloud while you have some thing on-prem, leveraging scalable infrastructure and redundancy while also keeping your core assets fully under your control. It's pretty easy to make an internal S3 replacement, it's hard to make a better S3.