That old story now appears to be apocryphal. Some people checked records and discovered Einstein had an outstanding academic career. I believe a lot of the stuff about him doing poorly stemmed from educators desire to show underachieving students that even if they didn't do well now, greatness was still within their reach. They held up Einstein as an example. "See, if Einstein was a poor student and later did great things, you can be like Einstein."
Hank