[Phil153]

Here's the thing. If you're sufficiently smart and knowledgeable, there are a great deal of things that you'll never be able to explain to most people. And there are some things you won't be able to explain to anybody. Not only that, there a great deal of things you're knowledgeable about that people just don't care about. It sounds like some of your problem is not grasping that fully.

Also realize that things you learn online are very different to things you learn in the classroom, on the job, or from talking to friends. All of these things are tagged with rich syntax, a memory of the speaker's tone and intent, and a million other clues you can never get from reading text on a screen. These are the things that give you the mental order and confidence needed to discuss a topic intelligently.

A final problem may be not aligning your communication strategy with your intent. Smart, overly analytical people tend to do this a lot. Why do you talk to people? Your real reason, underneath everything, may be a desire for attention or recognition or connection - and discussing dry intellectual stuff (which just happens to be fresh in your mind) is usually a very poor way of achieving that.

These things may not necessarily apply to you but they're something to think about.