“But how do you explain that many Sephardim were intellectual Geonei Olam?”
I’m not about intellectual capacity or accomplishment. I’m talking about approach in life. Ashkenazim like to intellectualize things. A couple examples:
Ashkenazim like to learn Gemara for lomdus, not for halacha. See the intro to the Yabia Omer, where he points out the need to learn halacha. Otherwise, people learn lomdus and can make huge mistakes because they think they understand. ROY points out that when an Ashkenazi student starts learning for smicha, he goes in the back of the B”M and kind of hides, as if he’s doing something shameful.
A non practicing Sephardi is generally philosophically Orthodox. He knows the real religion, but chooses not to follow. Nonfrum Ashkenazim, on the other hand, make a whole philosophy about their misdeeds. Hence reform, conservative, reconstruction, renewal, etc.