Just for my curiosity; did you use EBS or instance storage?

Back when we did this instance storage was much faster than EBS but the difference was not as dramatic as it can be these days. For example:

i3.2xlarge -> 180,000 write IOPS (4KB) 456$/month EBS 16TiB volume -> 16,000 IOPS (16KB) (more than 1,500$/month)

The difference in price and performance (NVMe can go much higher than this) could justify the EC2 self-hosted approach.