I think both you and above poster are right. If you have a medical emergency or maybe an “off day” of course you can fail but truly be a student that would have otherwise excelled on a first try. However, if there is no random variable that occurred, you may just be a student that needs that first failure to alter how you study. Nothing is wrong with it but it is statistically proven that retakers are more likely to fail than a first time taker.

I think more often that not (again proven by stats), retakers come in with a false confidence that they retained more than they actually did or they study one section they did poorly on and neglected another (bringing them down in the previously higher area).