Most people (sadly, even our parents or other people we respect) are not conditioned to update on a belief merely because it is true. Look at your mother's objections: she compared it to totalitarianism. If we take that objection at face value, then we know that she believes that such "narrow thinking" puts her at risk for totalitarianism, which is a risk she is not willilng to take for what is merely true.

Generally, if you want someone to believe something, you need to either trick them into believing that they already value what you are about to make them believe, or you need to trick them into modifying their values. This will be harder with your mother than with a stanger, as the idea has already been presented to her and she has parental authority to maintain. But there are ways to manipulate someone even in those circumstances, if that's what you wish to do.