It's just simple logic and examining the circumstances and context.
NBA was in dire straits, a mess. They needed a publicity stunt to garner attention, what better than to have some massive man-giant score 100 points.
Moreover, Wilt was a notoriously bad free throw shooter, no ocular proof, no video proof, barely any radio, all we have is Wilt with a piece of paper with 100 written on it
And it's tough to believe Wilt anyway because of his lying about the number of women he slept with, so his account of really anything in his life could be held up to scrutiny.
And even if he did do it, the achievement is decidedly not that special. He was playing a gaggle of part time chancers who had no business being on an NBA court.