For what it's worth, I think that was the premise of hybrid on-prem and multicloud. If you can trade-off availability in your stateless compute and worker layer and you're fine mostly managing it on prem, the cost savings could be very compelling. However, you'll still pay for bandwidth, which is the real killer and recurring expenditure. At the end of the day, there's no getting around that unless you move fully to your own metal, but then you'll likely realize costs related to maintaining your own metal that made you want to switch to the cloud in the first place. One way you might try to test this out is by using bare metal AWS instances -- if it's going on the right direction but you want more savings, you could move to using AWS Outposts with your on prem metal.

Just to make some conjecture here, I think that there's a difference between not liking the market's prices and thinking that the market is mispriced. Another commentator's point that the difference in bandwidth between AWS/Azure/GCP/OCI and DO/etc being a factor of 10x should give you an idea of some of the price discrimination going on.