Yeah, it's been said by many talents, but there's no profitability in Holo music unless you're selling related merch. People doing music and especially MVs are doing it to keep building awareness and audiences, or as a passion project. Basically to keep themselves in the game. Even very successful songs are a money sink, and a huge one if the video is any more than lyrics over an art piece.
I personally think it's true even of the most successful like Suisei, Mori, and Marine. That's why Mori pushes music-related merch, album purchases, blu-rays etc so much. Breaking even on streamed music or MVs just doesn't seem possible