why do some People keep silent ?

We asked the same question to our friend who often remains calm and keep silent about anything.

he answered as follow :

You’ve got some very comprehensive answers.

For me, and why I sometimes keep silent, I can think of two scenarios:
Avoidance of Conflict
If someone expressing political opinions that are 180 degrees from mine, I tend to just say “hmmm, interesting” and don’t bother to debate the topic.
I’m slightly concerned if I expressed my opinions, I would lose a friend. Is that the best decision? I wonder myself.
Fear
If I think back many years to the classroom, I would often keep quiet when I knew the correct answer.
That was fear of some sort. I’m not sure exactly how to characterize it. I guess maturity has cured it, so, it’s not worth the trouble to psychoanalyze.
Simply living life and experiencing all the ups and downs seems to cure a lot of phobias.

There could be multiple reasons. But if the person is silent around a particular set of people it could be because of -

a. They know they won’t be heard
b. They are afraid of expressing their opinion in front of considerable set of people (highly likely they know what they are talking about, yet uncomfortable)
c. They can just see through people and know where they are missing out and going wrong but don’t want to hurt them so they choose to keep quiet.
d. They tend to overthink. I know people who can mentally imagine the conversation before they begin to talk and thus refrain to begin it if they think it might not go in the right direction.
e. they simply love to listen. They enjoy listening to people getting excited at things and listening to them.
In my opinion the first point is the most common reason.