You’re allowed to want something your family doesn’t understand yet.

Wanting something nobody around you has done is harder than wanting a thing with a path already worn into it. The lack of understanding is often lack of familiarity rather than disapproval, and it tends to soften once there is something concrete to look at. You do not need your family to grasp it before you are allowed to pursue it. Understanding frequently arrives afterwards.

Instead of making the case in the abstract, take one small visible step and let that do the talking: a course, a tryout, a saved-up piece of equipment. Tell them what you did rather than what you plan. Progress explains better than argument.