Because I enjoy the craft. I will enjoy it less if I know I'm being ripped off, likely for profit, hence my deliberate choices of licenses, what gets released and what gets siloed.

I'm happy if someone builds off of my work, as long as it's on my own terms.

1) Ensuring that there is no malicious code and enabling you to build it yourself.

2) Making modifications for yourself (Stallman's printer is the famous example).

3) Using other people's code in your own projects.

Item 3) is wildly over-propagandized as the sole reason for open source. Hard forks have traditionally led to massive flame wars.

We are now being told by corporations and their "AI" shills that we should diligently publish everything for free so the IP thieves can profit more easily. There is no reason to oblige them. Hiding test suites in order to make translations more difficult is a great first step.

There are strong parallels to the image generation models that generate images in the style of studio ghibli films. Does that benefit studio ghibli? I'd argue not. And if we're not careful, it will to undermine the business model that produced the artwork in the first place (which the AI is not currently capable of doing).