Fails in resources

Why some personal information becomes susceptible of being accessed easily through some online resources?

Because people do not give you enough security you could have your account you dare the options that the application gives protect yourself from unwanted people or things that can ruin our lives just by not putting security to the account.

In addition one of the most effective ways to ensure more your security in social networks is to ask you what you are publishing? If I hacked that information that publish can hurt me?