The decision of your mom is right. You can't force anybody to be involved in Bitcoin to make an investment in Bitcoin. It A human nature not to believe until they do their own analysis, In this case, your mom first does not accept but when she hears from another person she believes. Bitcoin needs consistency and patience if you force someone then maybe he will work for just one or two days and then he will be bored because you force him to do this instead if you tell them nicely what is bitcoin, how it works, its benefits and also your profits are taken from bitcoin then I think your words will effect on him and will start some research on bitcoin and at last he start investing in bitcoin.