example: i learned XML in high school because i wanted to create a custom conlang dictionary for the macOS (then OS X) Dictionary.app, which was XML-based. this is not the most pressing issue which needs solving in the world, but it was a real problem i cared about, and working on it exposed me to all kinds of problem spaces in document processing, information representation, data entry ergonomics, as well as internationalization concerns, IETF standards (BCP 49!), and automation workflows for handling large amounts of structured metadata. that's the sort of thing which happens when you work on a real problem. you get exposed to existing solutions; in trying to comprehend those solutions, you gain an understanding of the broader concerns they are trying to address; you develop and mature and grow as a person. i don't care about conlangs anymore but i do still care deeply about internationalization.
in contrast, i can't think of a single thing i learned in a math class which meaningfully developed me as a person or a professional. i went into college wanting to be a math major,
entire field of cool solutions with no problems attached