what went wrong?...... we grew up

           I met this little girl in church, she was just running around , making noise , laughing , generally just being happy, I just took a second to take look at her and I could see that right there was a human who doesn't worry, fear, hate or have regrets. and that got me wondering where did we go wrong??
          it was clear that she had nothing on her mind but was just leaving in the moment and I definitely had thing I was worrying about (like what am gonna do with my life after graduation), she was the center of attention and no one passed any judgemental looks or comments at her, but as for me nobody really gives a fuck if I exist or not, and anything I do, someone must have something negative to say, she didn't have any fear , she didn't hate and even though she had all the attention in the room , she did not bother herself about what people think," she was so busy being herself that she had no idea of how utterly unprecedented she was" ( quote from fault in our stars).
             I still don't have the answer to my question , what went wrong?? that I don't feel this peace and happiness I could see in that little girls eyes, because we all tie our happiness to someone or something, an achievement , success. this little girl doesn't have anything and is as happy as happy can get. so what went wrong?? or what is wrong?? is it that we grew up?