You must also think "scale" and "market pressures" keep down the price of Windows.
Hint: AWS has wonderful margins because everything is tied together, and bandwidth charges to get data out are huge. S3 is a great solution for data used on AWS, but costs more than 30x Storj on bandwidth alone ($90/TB for outside access, plus the cost of doing cross-region replication).
If you're going to work from "first principles" it always helps to have the first hint about how markets actually work--and that different products make different trade-offs (local transfer speed and latency vs. cheap global redundancy)