It's usually pretty safe to be cold in a public setting. You might cause a few strangers to feel miffed, but that can be a good thing - especially if the strangers were trying to hit on you or get something from you. Being cold in public probably won't hurt your reputation or cause any long-term harm. That said, if you see someone in need of real help, lose your cold demeanor and lend a hand. Think about what you'd want someone to do for you in the same situation. There are times when being cold can help you win an argument, close a business deal, or score the winning point. There's nothing wrong with having a tough, cold attitude when it comes to getting ahead - unless you're taking it so far that you do real damage to another person. It's important to think through the consequences of your attitude and actions. Being cold to family and friends will only make you feel isolated. After years of being treated coldly, it's likely that no one but your parents will still want to give you the time of day. Being cold can have its benefits, but in the end, those who are  generous,  warm and  charming attract the most friends. Since having good friends leads to lifelong happiness, you might want to consider cultivating these personality traits once you've experienced what it's like to be cold. Don't worry, you can still flash your icy side when the situation calls for it.

Summary:
Be cold in public. Be cold when it helps you excel. Don't be cold to your family and friends.The people who take care of you and are warm to you deserve the same in return. Beware getting a reputation for being cold.