In-house vs Cloud Provider is largely a wash in terms of cost. Regardless of the approach, you are going need people to maintain stuff and people cost money. Similarly compute and storage cost money so what you lose on the swings, you gain on the roundabouts.

In my experience you typically need less people if using a Cloud Provider than in-house (or the same number of people can handle more instances) due to increased leverage. Whether you can maximize what you get via leverage depends on how good your team is.

US companies typically like to minimize headcount (either through accounting tricks or outsourcing) so usually using a Cloud Provider wins out for this reason alone. It's not how much money you spend, it's how it looks on the balance sheet ;)