I love this model of software development, which I think of as "artisanal", as opposed to open-source or enterprise. A small team, maybe just one person, who invests deep effort into a product that does one thing very well.

The question is, does it actually earn enough money for the person to live off?

In this case, no. It would be nice if it did though.

World would be a slightly better place if those who can afford (or put it on company) would support these indie developers.

This is exactly was my first thought. Having good paid product which at least covers the expenses of the developer is much better than having a product for just a love of it.

It's an open question in these times, though there's a cohort of "artisanal" devs trying hard.