The "why" view is the most uncomfortable and most valuable. Every subject on this taxonomy can be defended on prestige, on family expectation, on income, on calling. The honest defence is rarer: why does the world need more practitioners of this subject in the next twenty years, and on what specific evidence?
Demographic-decline societies (Japan, Italy, parts of EU) have a different demand curve for healthcare, gerontology, robotics-for-care, and inheritance-tax planning than demographic-growth societies (Indonesia, Nigeria, Pakistan, parts of India). Climate-transition demand is driving electrification, materials-engineering for batteries, environmental engineering for water and waste, and the entire "green skills" cluster identified by ILO and the EU. AI substitution is genuine in repetitive cognitive work but creates net-new demand for AI-human integration roles, AI safety, and the "AI for science" cluster.
School Is Cool's "why" view connects each of the 100 subjects to its macro driver, citing the specific reports, statistics and regulatory shifts that justify (or undermine) demand growth. Where a subject has secular tailwinds, the "why" view says so. Where it has secular headwinds, the "why" view says that too. The intellectually honest reader uses this view to sanity-check every subject choice against demonstrable demand evidence — not on prestige, not on family expectation, not on inertia.