Because that would be bad for society. It's important that money moves around as much as possible--every time it does, value is created. Think of it like the water cycle. By increasing the output of the sun (enacting laws to keep publicly-funded code private), we cause lots more money to evaporate from the taxpayer oceans (by solving the same problem repeatedly), and that in turn creates lots more fiscalonimbus clouds in the upper ten percentosphere (where you can find, e.g., large consulting businesses and shareholders). Before long, all that evaporated money (it's actually stock now, the most interesting property of which is that its value expands and contracts to fit whatever everyone thinks it should be worth) will start to precipitate when it's liquidated again, see? From there it rains on unspecified economic mountains and valleys, and eventually trickles back down into the ocean again.

You might point out that increasing the output of the sun in the real world actually result in a scorched, uninhabitable earth, and that also that's not how any of this works but hey, no analogy is perfect. And this one is plenty good enough to convince voters.