I know at least of Textual. Open source but you can buy a pre-built binary for $10. Compiling it yourself was fairly easy when I tried it out once though.

https://github.com/Codeux-Software/Textual

Yes, but it was sold to an acquirer by the original author.

Making it open source would have interfered with the author’s profit goal. There’s nothing wrong with wanting to make profit from your work and protect the source.

Likewise, you’re free to avoid software that isn’t open source. However, it’s useless to make these demands that someone should have open sourced their work when that clearly wasn’t in the best interests of their goals.

Except that it's not really true, since open-sourced applications can and most definitely have changed maintainers. And even if they don't, there's still a risk. Do I need to remind everyone of the xz incident when it's so recent?

Open sourced apps are absolutely vulnerable to this “attack vector”

Did you already forget about the back door in xz utils?