I enjoy the term author-entrepreneur coined by Joanna Penn. It encapsulates well how developing a sustainable writing practice is not much different from being a tech entrepreneur.
Making a living from writing is about showing up often, having something to sell, and putting your work in front of others. It's not forbidden to fail, to have co-founders, or to dedicate your workdays to writing. It's not something you can only realistically do on the side: it's a lifestyle, and this lifestyle is for anyone willing to give it a go.
Just like the indie bootstrapping movement is expanding, a new generation of indie authors free from the chains of royalty payment will appear. It doesn't make sense to give away so much to middlemen–anywhere from 5 to 60%+ of your revenues–when there are new tools and services to do everything you can dream of without any technical expertise.
A startup, let alone an indie tech venture, would never give away this much control without substantial guarantees. It's not surprising that, under these revolting conditions, the writing life seems so unrealistic to many. If you give away 20% of your revenues to a publisher, and another 25% in taxes, you are left with very little. Imagine if every software developer had to do the same to publish an app on the app store. It would not only hurt the developers, but also the very consumers the store is supposed to serve, and thus the store itself. It simply doesn't make sense.