re: Crackpot ASOIAF Theories SPOILERS

I think Rhaegar was looked on as kind of the equivalent of a renisance man in that world. He was a lover of books and reading. But at some point in his youth he read something that convinced him that he would be needed as a warrior so he turned himself in to a very good knight/medieval
type of warrior.

Also, I think he benefited by contrast with his father, the mad kind Aerys. There has even been speculation that he recognized his father's faults and that there may have been movements afoot (with or without his knowledge) to take the throne. I'm pretty sure there is no hard evidence for that speculation though.