Unless you have Tom Brady, most teams win a SB with a 1st round QB.
Except that this is really only technically correct: 27 Super Bowls were won by a quarterback selected in the first round of the draft, and 24 more weren't. Even without Brady's five Super Bowl wins, 19 out of 51 is not such a small sample so as to be irrelevant. Perhaps as significant: Sixteen Super Bowl-winning quarterbacks were drafted in the first round, while fifteen Super Bowl-winning quarterbacks were not.
My problem therefore with arguments for selecting a quarterback early is this: People argue on the basis of a stat that points in the direction of 51%, and then refuse to acknowledge every other pertinent piece of data.
Certainly you believe that all Super Bowl-winning quarterbacks were surrounded by one of the best teams in the league in any given year, don't you? Therefore you have to conclude that there's a whole lot a franchise needs to do right so that they can eventually win a Super Bowl, whether their quarterback is the most important player on the team or not.