I saw some one meter high transparent glass tanks, with 1/3 the depth of the liquid inside,soaking the numerous green PCB board, silent boiling and bubbling. Each glass tank have its own copper pipes, and connect to a small cooling machine. Steam condensed liquid in the above,occasionally, a drop down. LED lights are in the flashing constantly, which bring a lively active feeling.
This is the danger of BTC long-term. What happens when mining advances to the point there are only a few huge specialized facilities? They become targets, and the security of the network can be easily compromised. Plus, I can’t even imagine the amount of electricity one of those facilities wastes…shameful.