That $559 billion is including all the money the government (states, mostly?) already gives to schools that they then spend. GP was talking about (I assume) covering tuition, which is estimated between $50 billion and $75 billion from the articles [0] I can find. That lines up with ~10% of the military budget.

[0] one example: https://www.npr.org/sections/ed/2016/07/28/487794394/hillary...