There is an aphorism, dear reader, that goes: never try to teach a pig to sing. It wastes your time, and it annoys the pig (Robert Heinlein).
This is an interesting and incredibly useful concept to understand. Often-times we have excellent intentions to show another a better way, or we try to solve some problem that they are having for them.
This is a mistake.
Attempting to change another for the better will not only annoy and irritate that person, you will find that you wasted a lot of time and energy that would have been better spent advancing your own cause.
And often this is the only way you can really help anyone anyhow – through your actions and what they can see happening in your life, rather than anything you might argue or say to them. Once they see that you are at peace with “letting it be” they will pay more attention to you and what you are doing, and then approach you, fully receptive to what you have to say.
First take the plank out of your own eye, and then you will see clearly to remove the speck from your brother’s eye. – Matthew 7:5
To be fair, this is not always done in the spirit of trying to “fix” someone else; many people do this with the intention of helping someone out or showing them the way, or they see that someone they care about is going in the wrong direction and want to do what they can.
The problem is that this is not something you or anyone else can do. Unless you are in some way responsible for that person or you are approached specifically for such advice or help, it is best to keep your peace and let the person go his or her own way.
You have no responsibility to interfere in any way, whether that person be a friend, coworker, grown son or daughter, family member, etc. Keep your peace and you will be much happier for it – know that life will ultimately show that person what you already know and that you will be no worse off for not involving yourself or trying to stop some sort of harsh lesson that you saw coming.