Im in the process of purging data off s3. I suspect it will be about two weeks of work and I calculate it will save me roughly 250k over the "lifetime" of my product.

What I think too few people understand about s3 is that costs on S3 compound. Every month you not only pay for data you stored in the current month but you also pay for the data stored in every month previously.

S3 is a de facto standard supported by multiple vendors and open source technology. You can pick lots of other cloud vendors and use S3 there, or you can self-host S3. It's one of many AWS technologies that is not vendor-locked.

Yep, for ex: we use the exact same code to get/put files to DigitalOcean Spaces... the only thing that changes is a config value for the S3 endpoint. S3 is basically an open standard. The only vendor lock-in would be the time/money it takes to copy your data out of S3, but that's the same for anywhere you store your data... even when self-hosting.