rogue scholar
noun.

1. A person with extensive knowledge pertaining to various subject matters that extends beyond formal education. This person often gathers knowledge from various sources, such as media, friends, casual reading or the internet.

2. A person who attains knowledge from tradition sources, such as college, university or books, but studies the materials in unconventional locations, such as late night diners or parking lots.

note: This term is a play on words, based on "Rhodes Scholar."
example 1. Though Gary, a self-proclaimed rogue scholar, never even received a high-school diploma, his knowledge of physics and history is amazing.

example 2. Karl studdied his math homework all night at the Texan while drinking coffee. In spite of the noise and distractions, the rogue scholar did very well in his class.