Just scanning W'pedia's bio-article regarding Thomas's early life and education, the first thing I noted was that he was born in 1948, and did not delay entering college. More to the point, Thomas went through college before Affirmative Action had become a thing. Further, Thomas did not go to public universities. After a year at a Catholic seminary (which he left due to the racism he experienced), he entered College of the Holy Cross in Massachusetts as a sophomore on a full academic scholarship. English was Thomas's second language - Gullah was his first language - but he majored in English. Thomas graduated cum laude, ninth in his class.
Thomas applied to and was accepted by the law schools at Harvard, Penn, and Yale, three Ivory-League schools. He chose Yale for its financial aid package. He received his JD from Yale, again an honors graduate. In the real post-graduation world, some law firms chose not to employ him because they ASSumed he was an Affirmative Action grad. He found his first job with MO AG John Danforth, becoming an assistant attorney general for 3 years.
Thomas was a a legislative assistant to the US Senate Commerce Committee and later assistant secretary for civil rights at the U.S. Department of Education under Reagan. All in all, Thomas got where he got with hard work, academic diligence and excellence, and more hard work. Unsurprisingly.
ETA: As USSC Associate Justice, Thomas asks relatively few questions when cases are being heard. Progs pretzellate this into "evidence" that Thomas is stupid. In the real world, even as a college student Thomas was noted for being quiet and reflective. IOW his relative lack of questions reflects Thomas's personality and having studied the cases and the supporting briefs.
Like elementary-school bullies, Progs are picking on a noticeable quality. Were Thomas a vociferous questioner and speechifier, Prog-Haters would mock that instead.