Your last point is the important part: depending on the type of infrastructure you need you might be able to save money. If you want a cheap place to dump your files, B2 is cheaper than S3 and raw storage hardware pays for itself in about a year. If you need a sophisticated CDN then yeah you’ll need to be huge before it pays for itself. I would consider ditching S3 at the point where I can hire two full time engineers to worry about my storage layer.