Decades ago people would run aquariums as screen savers, when some folks figured that you could use those computer cycles for good, such as the medical research that a few dozen FReepers do for Folding@Home.
Bitcoins use a form of encryption to secure their value (hence, “cryptocurrency”). They can be “mined” by running extremely intensive math formulas to find new, unused ... numbers ... and make new bitcoins.
Once everyone moved from CPU calculations to GPU calculations, companies such as NVidia have exploded in value, as young Asians buy hundreds of the latest high speed video cards and cram them into servers, and the servers into racks of servers and the racks into FB, AMAZ and GOOG style data centers.
$16,000 per day is probably 50% to 60% profit but the cost of buying enough equipment is pretty high.
I'll find some related articles and post them.
“Once everyone moved from CPU calculations to GPU calculations,”
They moved from GPUs to FPGAs to ASICs several years ago :-) ... they’re using racks and racks of ASICs doing the operations to mine BTC now ... ASICs are the lowest power, highest performance solution (and also the reason why it’s not very cost effective to mine BTC on your home PC these days since China all but cornered the market on mining BTC cheaply, quickly, and efficiently).