That's definitely true. Even with 4KiRAB paying more than FUNimation, I would imagine that most people at 4KiRAB, as well as many other recording studios, aren't able to live off from their voice acting. The only exception seems to be for the well-known voice actors who take enough multiple roles so that they can live off from that career. Most other voice actors, as you mentioned, have done other careers, such as theater and singing careers.
Yeah, I was impressed that so many famous musicians gave him such nice reviews on his website. I love his voice acting, but I wouldn't be bothered if he wanted to concentrate on his music career either. It would be completely understandable and as long as that's what he wanted and would make him happy, then I just wish him all the best and hope that everything works out for him.