Do you really think anyone lives their whole life stupid because someone else thinks they are? No, they live their life stupid because they choose to, and they use others as their excuse.
I couldn't read when I was eight, I went through three years of infant school class with the same teacher, and all she ever told me was I was too stupid to learn, and I believed her because she was the adult, and I, apparently, was the idiot. In my next class, with a teacher who didn't tell me I was idiot, I learned to read [and thus write as well] in a very short space of time, I was eager to, because it meant I wasn't stupid after all.
It's possible my first teacher was just terrible at her job but given she managed to educate other kids it's equally likely she just didn't like me, or kids from a poor background [it was mainly a rural community school with a few barbarians at the gates such as myself]. Whatever the reason her ignorant and less than pleasant opinion of me made a difference, a damaging difference, lowered my already fairly diminished [read non existent] self esteem, none of which I got to choose. I lived three years believing I was too stupid to learn to read, my parents lack of interest ensured it wasn't discovered until I changed classes, I didn't choose any of that, I got chosen.
So, do I think anyone lives their whole life stupid because someone else thinks they are? Yes I believe that's entirely possible given the right circumstances, and given sufficient ignorance and cruelty from others.
Glad you got sorted out and that some cared.
I read a story in my Facebook newsfeed a day or two ago of a neglected child of four years old who was picked up by social services and when asked what her name was she said "Idiot".