People can say whatever they want to say about Bitcoin. Their opinion shouldn't matter to you.
Yes and if you dont use Bitcoins, they may also laugh at anything else. I think the best idea is to see what suits you and carry on with that, discuss your family and then take decision in case you feel confused.
I do agree that people laugh only when they don't understand properly the fact of some plan and other than that are the previous fortune programmes who created negative image in minds of all as well might be another reason for them to laugh.