How does it make you feel when someone makes a statement to you that shows how little they get you, and yet they're convinced they have you figured out?

I’ve had that happen on here before certainly, although, to be fair, it is no doubt due to people not knowing me that well. Today I was told by someone that the only reason I like to help people is because it gives me power over them, that I can hold it over their heads.

WTF?? (Excuse my French initials)

This person doesn’t know how much I like helping others, how often the opportunity to do so has turned my day around from the good feeling I get from helping them.

Why would someone who has known me for less than three months tell me that?