I do not know how it happens in other countries, but here in Russia many people learn English all their lives. We learn it at school, at university, at courses. But we continue to remain silent, instead of speaking English. What is the reason? Once I attended an event, there were a lot of people from Asia and Africa. Many of them were not afraid to speak with mistakes. Knowing a few words they tried to talk. (I mentioned them because this issue does not apply to many European people studying English as European languages belong to Germanic languages that have much common in grammar and sentence building)
I thought then maybe we're very shy or maybe we're afraid to make a mistake due to perfectionism (in a good way)?
or it is that fear from the school: I'm afraid of getting a bad evaluation and to be scolded for this... How to overcome this fear? Even now having written this monologue, I think how many errors there are, what the native speakers will think about this and so on.