This quote is the most telling to me: “I want to work in the anime industry for the rest of my life,” Mr. Akutsu, 29, said during a telephone interview. But as he prepares to start a family, he feels intense financial pressure to leave. “I know it’s impossible to get married and to raise a child.”
He knows it's impossible to get what he wants in life, as an animator, but he still wants to do it for the rest of his life.
This isn't the case for most of the "jobs" that people are mentioning in the comments here, like people don't dream of being "cleaners" for the rest of their life, but there are other reasons why that might seem like their only reasonable choice. Lack of other marketable skills, probably being the most common. For cleaners, it doesn't even require that they can speak English, just that they can do the job they say the can.
My personal theory on anime, as that's the specific subject of the article, is that if there were a much lower supply of competent animators and the animations were more expensive to purchase, they wouldn't be so popular, people would find other things to do/watch, etc. Which really boils back down to supply and demand. It's not as simple as "people demand anime", but more something like "people are willing to pay $x for y hours of time watching anime", where services like Netflix (or more specific to the subject of anime, Crunchyroll) charge some small amount per month and give access to hundreds of seasons and full movies. If the masses had to purchase each season or episode individually, I'd suppose people would be watching a lot less or pirating a lot more.