Good question. I thought it would be a no brainer to put it on s3 or similiar but thats already way to expensive at 2m/month without api requests.

Backplace storage pods are an initial investment of 5 Million, thats probably the best bet you could do and on that savings level, having 1-3 good people dedicated to this is probably still cheaper.

But you could / should start talking to the big cloud providers to see if they are flexible enough going lower on the price.

I have seen enough companies, including big ones, being absolut shitty in optimizing these types of things. At this level of data, i would optimize everyting including encoding, date format etc.

But i said it in my other comment: the interesting questions are not answered :D