What does this " 不会 " mean in Chinese?

A. I really thank you for It’s already cost you so much effort to help me.
B. 不會 = I haven’t cost so much effort to help you.
A. Don’t ride a scooter on city streets, it’s so dangerous.
B. 不會 = I don’t think it is dangerous to ride scooter on city streets.
A. Do you know how to solve this math problem?
B. (我)不會 = (I) don’t know how to solve this math problem.
A. Don’t be addicted to him, he’s too young to trust.
B. (我)不會 = I wouldn’t be addicted to him.
So, “不會” is not a phrase trying to look down on someone and it has no insulting meaning and also no sarcasm connotation or making fun of someone. What you heard might be short-words for something, so you might confuse its meaning.

P.S. Oh, as you definitely know that facial expressions, voice volume, a voice tone, and physical actions prevail over wording’s basic meaning. So in some cases, especially when you watched action movies when someone said “不會” with the above characters, then of course, a normal wording would become sarcastic or even insulting wording.
I think, Chinese, like any other languages, don’t lack insulting wordings. But basically it’s not the term of “不會”, because it is a normal term used by everyone in everyday spoken language.

It is possible
May be

Google Translate says it means "Will not", "unlikely" or "that won't happen."