My writeup: https://keithalewis.github.io/math/um.html for modeling and https://keithalewis.github.io/math/uf.html on now to more accurately reflect the real world. I have taught Derivative Securities at NYU, Columbia, Cornell, and Rutgers over the past 14 years, but my day job is turning math into software that produces numbers people running a business will pay for. The textbooks are missing some important things.
The most valuable commodity in the world is trust. You can't buy it, it can't be manufactured, and it can vanish in an instant. Crypto currencies are used to take advantage of trust. Shamans have existed since the beginning of recorded history to take advantage of gullible people. Blockchain technology enables that on a global scale. P. T. Barnum was right.