- Learn to edit well, it's how to write well. Nothing opens doors like clear writing. For sources of quality edited writing, read The Economist, Quanta, and the first novels by authors who wrote 20th century literary fiction. Their later ones had less editing.
- Negotiation + game theory. Learn the traditional methods, and then forget everything you know about them because the real world has changed and broken the assumptions that went into the formal theories, but you need it as a foundation.
- Basic vehicle maintenance and repair. Even if it's just buying an ODBII connector for fault reading and being able to trace fuse box connections. Also, learn to drive stick, or be dependent in an emergency on someone who does.
- Learn confidence and humility by mastering a common physical skill like an instrument, singing, or performing monologues, etc. Not stupid tricks, but something where other people are objectively way better than you are and plan to be embarrassingly bad at it for at least a decade.
- Negotiation + game theory. Learn the traditional methods, and then forget everything you know about them because the real world has changed and broken the assumptions that went into the formal theories, but you need it as a foundation.
- Basic vehicle maintenance and repair. Even if it's just buying an ODBII connector for fault reading and being able to trace fuse box connections. Also, learn to drive stick, or be dependent in an emergency on someone who does.
- Learn confidence and humility by mastering a common physical skill like an instrument, singing, or performing monologues, etc. Not stupid tricks, but something where other people are objectively way better than you are and plan to be embarrassingly bad at it for at least a decade.