People use others insecurities to manipulate them and they don't even realise that there being used... and seems like age has nothing to do with wisdom... Once entrapped by vanity, ego or insecurities
I've often wondered what makes people do the things they do and always found petty reasons behind their actions.
The power of these people relies on your trust and their tell is that they isolate you from the rest of the world and fuel your paranoia that everyone is against you and only they are your true well wishers.
True friends tell you the bitter truths and never try to isolate you. Deceivers try to isolate you for only then they can keep feeding you their lies and using you. Once you stop talking to others and weighing in their input the circle starts, your distancing with your true friends inevitably drives them to distance themselves from you.
They only thing one can do at that point is try to show the friend the bitter reality but most often the only thing one can do is wait cause their paranoia won't let them listen to you. You wait for it to all fall down with its own weight....