why does everyone think that i'm a childl ????

its seems to be that here latly everyone around me thinks that i am just this dumb person that doesent know anything about nothing ? I try telling people what i think about things that happen around here ,but they all act like i'm this dumb ass person that is 100% full of shit with nothing to show fro the things that i know ,and the things that i have done within my own life . I know so much more then these people think i do ,and yet when i damm cop sides with yet they still think that i'm over reacting about things well from now on i have just desided to be this person that does not' talk speek or say a damm word about anything to anyone anymore. the reason being I will try and explane a littel bet later alright.