I tend to have a visceral reaction when indie devs proclaim that paid software is "over". (Which is not what David Smith is doing, but what a lot of commentary in this genre tends to look like.) It's not that ads are inherently bad — podcast sponsorships, The Deck, and affiliate links tend to be decent and respectful — but what kind of software future can we look forward to if the only way to make money is to sell our UI real estate to the highest bidder? There are many ethical lines that are all to easy to cross in the pursuit of profit. This is the same path that has turned mobile games into exploitative, IAP-driven casinos — and the web into a murky bog of autoplaying videos and 10-second load times.

Here's my opinion: pay-once software will never disappear. Not now, not on an infinite timescale. For things like Twitter clients or text editors, sure — it'll be very difficult to sell your wares at a premium when there's so much free competition. But certain pieces of software are just too unique to be cloned. Nobody minds paying money for Model 15[1] because it's the only one of its kind. Maybe instead of spending years and years working on a single productivity app, we should focus on building stuff like that.

[1]: https://www.moogmusic.com/products/apps/model-15-app