cultural context is another reason, and probably a main one in the situations you describe.Keit said:Because when you learn a new language, you put an effort on proper spelling and grammar.
You pay attention to any small nuances, because you try to understand what is said or written. [..]This is why, unfortunately, most of the Russian speakers prefer to "hang out" on russian forumes. If you don't have any specific and important reason to develop sufficient communicative skills with other people, you prefer "more comfortable" environment. It's can be labeled as a general lazyness
and probably, in most cases, this is a true reason. But I think that we all prefer to talk in our "mother tongue" because by translating ideas from one languadge to another, we miss part of the meaning or energy.
Words carry more then simple meaning, they carry intent or some sort of energetic signiture that can help other person to understand it more easily. It's also carry the "unspoken meaning"/semantic meaning that can be understood only by natives/mother tongue speakers.
Beside a simple meaning and an energetic signature, words mean a lot in relevance to a sounty and culture-specific situations you lived through, the books you read, the jokes you grew up laughing at. A lot of our communication is subtle quoting / referring to this shared cultural heritage.
This gives depth taht is otherwise missing. Lazyness per se IMO has little to do with choosing a more 'comfortable envronment'. It is more like 'birds of a feather flock together'.