If everyone does it is it true?

So back in school I was placed in the smart classes. Thsi led to my aunt and cousisn to constantly tell me how I was dumb or too dumb to be in those classes. I tried to ignore it but eventually it started to be some of my class mates. I Mm really not dumb. I was actually making better grades than some of them who had been in the classes for years. But after so many people started to call me dumb and stupid I had no choice but to believe it. I still think something is wrong. But I know I’m not dumb. Now I’m 20 going on 21 and people still talk to me in a degrading way. It hurts but I go with the flow. I’ve let it persist for years and now I know everyone thinks that ablut me. Even new people. I don't know if I give off a weird vibe or what. But people automatically say the rudest things to me. But now that I think about it. My friends tell people I’m dumb before they meet me. It’s so I don't know. I feel like I’ve become some kind of joke or scape goat. How do I stop it or are they just telling the truth?
If everyone does it is it true?
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