Diversify for the future. Yamada Darkness is young and quite aware that the hololive ride isn't forever. But most importantly she knows all of her brand cannot be tied to holo as when she eventually graduates, and that is a certainty with all vtubers, all she'll be left with are her sidegigs that she undertook, such as this fantia page.
I can't fault her because I would do the exact same thing; having Yagoo take 30% of what I make is one thing, having Susan Horsefucker take a bigger bite, then being taxed, and no wonder you see Noel posting her tits, AZKi still keeping an IRL office job, etc. And to answer the final question, yes the JPs need money really bad, especially now in faggotworld inflation crisis-time.
With that said, you still see vtubers punching in, clocking out like it's a job at the auto assembly line. The bare minimum, no passion or enthusiasm left. Maybe a sponsored game or tie in stream, then that's it. Again I don't fault them because entertainment is a clown's life, it'll devour your soul and drive you into some form of narcotic or some other vice as coping mechanism.