Me too. But the problem with "the economics just aren't there" means that if I cannot get, just from word-of-mouth (say, a Show HN post) 100 users @ $10 once-off lifetime purchase, then this is not a product that is in demand anyway. An open-source/free product that is exactly the same would similarly receive no love from users.
IOW, if not enough users exist for this product at $10, not enough users exist for this product at $0. Your passion product will still result in the dev burning out on the fact that no one wants their passion enough.
I think you can argue that, if you have enough demand at $10, that you’ll have enough at $0, but I don’t see how not having demand at $10 implies that you won’t have demand at $0, since usually making something cheaper can change buyer’s minds.
My point is not that the user would go without. My point is that if your product is not desirable or differentiated enough that enough people would pay $10 for it, then making it free won't help because it will be lost in a sea of clones that already existed before you even started working on your product.
After all, look at your list - todo list apps, time tracker apps and budgeting apps; you cannot, in the sea of free competition right now, deliver a desirable enough app in any of those classes, unless it provides so much value over and above the others that many people are willing to shell out $10 for it.
IOW, if the product does not provide enough value for some people to pay $10 for it, making it $0 won't make a difference because it doesn't provide anything over and above the entrenched free offerings.
why this couldn’t be SOMEONE’S ELSE passion project