One of the most worrying things I hear from PhD students is, “I already know what the answer will be.”
The whole point of research is to discover something new. So a researcher who says, before they have done their analysis—or, in some cases, before even starting their research—that they already know the answer is limiting themselves to what they already believe.
Of course it’s sometimes necessary to make predictions based on what you alredy know, but these should be the starting point. Your job is not to prove your hypotheses but to test them; a process that often leads to discoveries you never could have predicted.
But if you think you already know the answer, if your mind is closed to new discovery, if you’re unwilling to be proven wrong, then you’ll never make any worthwhile contribution to your field. At worst, it can lead to academic fraud; manipulating results to fit predictions and misusing metghodologies to give the illusion of academic rigour.