It’s a bit of a strange argument that developers can feed their families _only_ if they sell their software on a subscription basis. Nobody wants to developers to starve. At the same time it is not a _duty_ of users of a software to make sure the developer’s family is fed. It is a business. Developer sells something, and the buyer gets value in return. Subscription is just one way of making the buyer pay more(may be hoping that they forget that they were paying for it amidst 50 other subscriptions).
It is perfectly fine to say “I expect to feed my family with this work. So I want to charge $bigamount”. Then your buyers chose whether your software is worth that or not.
You may also say, “I prefer a recurring income, and don’t want to charge one time. It is my prerogative.”, but arguing that one cannot feed their families any other way is disingenuous.
Another way of looking at it is - software is not very different than ebooks. Imagine if an author of a book says “Books should only be sold as subscription. It’s almost as if my readers don’t want me to feed my family!” If every reader is not continuously paying me $5/month, how can I keep learning and providing little updates to this book, and make errata?! How dare they try to get my knowledge at once when they can be paying me so much more to keep me fed?!
It is your product. You alone have the power to set a price. You may want to do market research to figure what the users would like to pay for it, but you can still decide to go higher or lower than that outcome.
I’m perfectly fine with a software product that is on the expensive side if it justifies its value to me as a user. This particular product I don’t have a professional use for, and cannot give you a number value.
You may also say, “I prefer a recurring income, and don’t want to charge one time. It is my prerogative.”, but arguing that one cannot feed their families any other way is disingenuous.