That sounds unlikely unless those machines had access to crazy disk I/O. A local RAID 5/10 with 8 drives would still take 30-50 minutes just to read that much data. Even with a mid-range SAN you still would have spent 15-25 minutes just reading data. This assumes 7.2K SAS/SATA since SSD/NVMe were not ubiquitous in 2015, but even with 2015-era SSDs you're still looking at half that much time spent reading.
In practice even NVMe SSDs at the time were maybe 10x faster for sequential R/W and maybe only 200-500x for random I/O. Most databases in 2015 were limited by serial dependency chains like walking a B-tree to figure out what nodes to read next and couldn't max out what an NVMe was capable of. Not to mention we were stuck with libaio in 2015 that made O_DIRECT ops synchronous.
So the OPs claim of reading multiple terabytes of data in seconds on AWS in 2015 literally wasn't technically possible.
SSDs simply were not as ubiquitous in 2015 as they are today, and I didn't know anyone using them outside of mission critical systems were the cost made sense.