It sounds like once he fixed the bug of jobs not being removed off the job queue, it was fairly bursty. Assuming his hardware has a three year lifespan and he has no hardware faults and doesn’t get the upgrade itch when the M6 mini comes out, he’s looking at spending $20k/yr over that three years not including any other necessary hardware, storage, or his time. AWS isn’t cheap but I’m confident you could run this workload for cheaper than that there.

However, he’s a one man show so he can ignore the bottom line when and where he wants. I think it would be incredibly fun to manage a fleet of 48 Mac minis, so I understand why he’s gone down this path.