Cpu:Intel Xeon E5-2697 v2 12 core - $2,524.00
Motherboard: ASUS Z9PA-U8 - $277.99
64GB 16x4 (4 slots still free) - $720
PCIe ssd:480 GB - $1007
Power supply 1500 Watt - $374
Video cards: ??? not currently available
Apple with similar specs: $7,899
So that leaves $2,723 for video cards, I can't find any suggested prices on the D500 or D700, except that Apple charges $300 per card to upgrade from D500 to D700.
Of course if you wanted 12 cores you could save a bundle and just get a dual socket board and 2 6 core cpus. Also the MB supports a lot more ram etc, but is a lot bigger.
Except the initial investment was a tiny amount of CPU time. The person who wrote the original software made a ton of BC when it took no cost to create them.
And who created the bitcoin software? We don't know but I'm sure they are having fun selling off coins they got for free to suckers who just finished eating their tulip bulbs.