Overconfident thinking is flawed because he does not take all
possibilities into account. One may understand the task at hand,
the support of his fellows, and the ramifications of his success,
and he may have even planned for unanticipated factors—but he has
failed to understand his own capabilities. He has planned only for
success, because he has concluded that there can be no failure.
Every person, in every task, should prepare for the possibility of
failure.