How do you develop the personality of I don't give a shit ?

I know this is stupid question to ask but I just feel like people who are outspoken and don't care about the opinions of others are truly so confident from inside. You can tell them from the body language or their presence. I guess some people are just naturally very good communicators. But being an introvert shy type person, I just hate the fact why am I so always nice to to others and deep down dont even like it. I just wish I could carry some ego and arrogance. Being nice is not ideal for modern society.