The "Insufficient unto the day are the troubles thereof" AntiPattern.
KentBeck mentions how his grandmother cautioned him against BorrowingTrouble. Presumably this is what birthed one of the underlying goals of ExtremeProgramming: Realistically asking yourself, "Am I speculating because it's helpful, or because I'm borrowing trouble?"
Here, "to borrow trouble" means "to take a course of action that may cause harm." (see http://dictionary.oed.com/cgi/entry/50025423)
As you go through your programming career, you'll find an astounding number of people who seem to be addicted to BorrowingTrouble. Why is this? The answer varies:
Their past experience has taught them, "If I'd only thought ahead, I wouldn't have had this problem now." They've learned that some speculation can do some good, sometimes.
They've taken the above observations too far, and don't know that RidiculousSimplicityGivesRidiculousResources. They are taught by peers, books, and mentors that the best way to deal with change is to predict it. Hence, any time they fail to correctly predict change, they scold themselves and swear to speculate even further ahead next time. CognitiveDissonance does its thing to counter the observation that maybe, just maybe, the cost of the rework is less than the cost of the speculation.
Two words, one WikiPage: GoldPlating. Try to apply HanlonsRazor and assume that this isn't their motivation. (This advice given by someone who is desperately trying to follow it)