I started because I was super into Japanese music. This was almost 10 years ago already. But over time I’ve come to appreciate the lenguaje itself. Especially Kanji. Now I love it, and is the main reason why I still go out of my way to learn new vocabulary that I may never use.
That being said, I’m also trying to get into a Japanese university for my masters degree, and I use Japanese every day at my job, so it has financial and professional uses for me as well, and has sort of gone beyond a mere hobby at this point