For under $50K, I have 4 machines with an aggregate 1TB RAM, 48 cores, 1 pricy GPU, 16TB of fast SSD, 40 TB HHD, and infiniband @ 56GB/sec. Rent on the cabinet is less than $1K/mo. It's going to cost me about $20K in labor to migrate.
So the nominal break-even point is six months but the real kicker is that this is effectively x10-30 the raw power of what I was getting on the cloud. I can offer a quantitatively different set of calculations.
It also simplifies a bunch of stuff: 1. No APIs to read blob data -- just good old files on an ZFS share. 2. No need to optimize memory consumption. 3. No need for docker/k8s/etc to spin up under load. Just have a cluster sitting there.
There are downsides but Coloc beats the cloud for certain problems.