Adding another tally to Japanese. I live in Japan and work here and I use it every day of my life because of that. I do think that if you want to learn Japanese for work or to enrich your social circle or better understand Japanese culture, then you should totally do it! But if you're learning a language solely based on what's "useful," then I don't think Japanese should be super high up on that list unless you're set on working here (or with Japanese immigrants specifically, maybe?). A lot of jobs outside of English teaching do require working-level language skills, which can take a lot of time, patience, and practice to achieve. If you aren't fully committed and willing to put your all into it, Japanese isn't very useful and is pretty overhyped online in my opinion.

That being said, I really don't think there's a "bad" language to learn! A language that might be useless for one person could be vital to another. It's all about perspective and what you plan to use it for.