It's stupid to marry young if one (a male, as for females there are certain biological issues after they hit 30) is good looking (some people have genes/looks that enables them to "date" for as long as they want...) and rich OR has an obvious potential to get rich. Most of the time such a person if marries young - will end up dovorced as it takes a will of steel to refrain from life "adventures" when you "have it all". Mid-life crysis is a myth to get more people to go to mental "doctors".. Some people are miserable and regret everyting from a get go, some just enjoy it whatever age they are (once again - if they have good genes and are rich). Simple as that.
For the rest (short, ugly, broke, etc..) - marrying young is good and preferable as they won't be able to find "the right one" when they are older.
And we all have a good "sense" of what kind of situation we are in. Look at people from your school for ex. - the uglier/less potential people were, the sooner they married, usualy.
It's all relative.