“Your most unhappy customers are your greatest source of learning.” Bill Gates
Feedback is how we can understand and improve. Positive feedback makes us feel good and keeps us on the path we are on, and is needed if we are headed in the right direction.
But being told we are screwing up is the best feedback possible because then we can stop doing something stupid or destructive or wasteful. Negative feedback is valuable, even if it doesn’t feel good in the moment.
An unhappy customer tells you they are unhappy because they actually care about your business or product, or you as a person. If they didn’t care they would just walk away and not say anything to you (but probably tell others about the bad experience). The fact they expose complain and your problems is a GOOD thing, because they WANT you to get better.