This pdf (https://f.hubspotusercontent30.net/hubfs/8968533/CS-2%20Data...) says the power supplies are 6+6 redundant 4kW supplies. Assuming 100% utilization (not realistic, but it makes the "math" easy) that's 24kW of "power supply".

If we presume the wafer consumes a large percentage of that (say 20kW out of the 24kW max) and that they are feeding the "wafer" with DC at 1v, then they /do/ need to feed in 20,000 amps to deliver 20kW of power at 1v.

So yes, 20kamp is a lot of current, but it is within the "power budget" the device seems to express in its marketing material.