I started playing music because that’s what my friends were doing. We used to draw comics together, but then I grabbed a bass guitar and said to my friend, “How does this work?” And I’ve been an overwhelmingly adequate bass player ever since.
While I expected a learning curve and to eventually be required to know what a “chord” was, I didn’t expect the other responsibilities. This doesn’t hold true of all musicians, but most wear quite a few hats. Sometimes they’re of the leather cowboy from hell variety, sometimes they’re the hat of an entire other occupation.