We need to be careful about social privacy and security, but I know and guess that hackers can get into our personal zone breaking security system, therefore security stuff is meaningless. How can we know whether our friends are hackers or not?

You'll never know unless one tells you or you catch them doing it. Almost anything can be hacked by the pros, so the best thing to do is ? Don't worry about it unless you have millions stashed and are worrying about it being ripped off. You'll find the most hackers on social media sites. Prime place to get the info they need.

Anyone can be a Hacker.

Side story.

I knew a woman who knew a woman that was her best friend they were friends for like 20 years the woman stole the woman's identity purchase a house was living in the house and still pretended to be her friend. I don't remember how she found out about it but she was just devastated she knew this woman for 20 years and they were supposed to be good friends. You can't.