I worked at a SaaS that had a 220 million a year bill. We did a ton to reduce the bill (reserved instances, right sizing, etc etc). 2020 rolled around and the business decided to cut back, we were able to save 20~% with being more aggressive with spot instances, moving from vpc connections via transit gateway to more peering, swapped to karpenter, etc. If there is anything I've learned is that there can always be money saved.