You just got a speeding ticket, your grades were embarrassingly low, you got caught sneaking out-- whatever the cause, getting the dreaded phrase from your parent "I'm not mad, I'm disappointed" burns.
It's deeper than an angry yelling battle because it cuts at the person your parent sees you as. Emotions from fights cool off and the words thrown de-escalate, but the disappointment sits on you like a mark on your permanent record.
Sure, twenty years time this will seem like no big deal and you might even laugh thinking back on it. But it always has that potential to be that dig of "well, do you remember when...?" to keep you in check even years after the fact.
It's especially difficult coming from a parent that you're really close to and really look up to. My mom is my personal idol and I'd rather get a double root canal than hear those words from her. It's like letting your #1 fan down or your hero and it's a hard feeling to shake. Their disappointment rubs off onto you and now, if you're remorseful, you'll be knocking yourself in the head thinking "Why did I do that?" for weeks.
It's a tortuous cycle but what you need to keep in mind it is just one instance. Although humans are typically known for their actions, it's usually their impactful ones. Do you ever hear about that one semester that was particularly rough for one of our presidents? No, you hear about their policies, whether that be good or bad.
I'm not suggesting you go on a robbery spree and expect this tough, but potentially forgiving response. In that case, you will be known for what you did there.
I guess what I'm trying to say is, try not to take it too personally when your parent says this. Pick yourself up and prove them wrong. Besides, the best revenge is success.