I've only heard that in the “brilliant kid, what a waste” quote describing his reaction to learning that Gates had left academia to start a company, which is a little less dramatic sounding from a then relatively early career professor but, again, the point is not that Gates was stupid but rather than his intelligence was only part of the story.

If you look at software of that era, he wasn't doing something nobody else could do. They had a BASIC interpreter, but it wasn't the first or notably better. MS-DOS certainly worked, but it was at least heavily inspired by CP/M even if the plagiarism accusations were wrong. Being a capable programmer was necessary to his success but it was far from the reason: there were many others around, and they did well but the legendary wealth came to the person whose mother was on IBM's board when he made that company-defining sale. He subsequently executed well but again not uniquely so — anyone who used Microsoft software of that era could tell you that it wasn't the quality of that software which kept people using it. He executed well, and certainly wasn’t shy about an … aggressive … legal strategy but there was also a substantial portion of nepotism and luck.

The world has many people who were smart and hardworking but will never be close to that level of success because they didn’t have the family connections, startups capitol, friends they made at the right school, or the freedom to make a big gamble.