No, because my best friend is a girl, who is also my twin sister. I wouldn't want to marry her!
Joking aside, I personally wouldn't mind marrying my best friend (if I have one from the opposite sex). I don't think it's wrong. I have heard stories where best friends become happily married. There are of course some downsides, so it's really up to the couple if they could work it out. To me personally, it'll get difficult for me. That is why I refrain from being too intimate with the opposite sex. Sometimes, the line becomes blurred between friendship and love. Some people might confuse the two.