That's what struck me seeing it with the tags "gaslighting" and "abuse". I know the original quote is attributed to Eleanor Roosevelt, and it's supposed to make you feel empowered, but I feel this is a better explanation of why it's hard to "just" shrug off people belittling you, being condescending, trying to tear you down.
If you say "I feel x because someone said/did y" the response is often "don't let them get to you" but honestly, that can be easier said than done.