Why do people disbelieve me when I am telling the truth

I am telling the truth about what I did and people disbelieved me and they always spread rumors about me and most of the time mock me and try and read my mind and talk behind my back. Especially when I try hard at my work. They assume I am a looser even though they tell me I did great.

To be honest with you people these days only care for them self's making them selfish people don't care about other people anymore it is very hard to find a genuine person in the world in our time as long as u know it's the truth that's all that matters belive in your self and u will go far I'm from the UK so u might not understand it when I say chin up it doesn't really have a meaning but if u think about it u will understand what it's ment to say