Presumably you could meet the boundary with "a dollah fifty in late fees at the public library" and find a way to push through from there. You'd have to find a way to publish or share your new knowledge. Studying at uni gives you access to experts in their own thing that likely have knowledge that could help you with your thing as well as a system designed to churn out these papers when you eventually find your thing.

Every day people discover new things but it takes attention, effort, and will to PROVE it's a new thing and more yet to share that with the world. Too bad you can't get an honorary PhD for doing that, at least not reliably.