He may be a legal adult, but it sounds like actual adulthood deferred. You are obviously living under your parents roof, and the discussion about not having access to the funds makes me wonder whose money it actually is. Maybe I am off base, but that is how I interpret your comments.
Skydiving is an adult sport for adults that sometimes like to act like children, but for the most part we are all living under our own roofs, or on friends couches, and we get to make the choice to waste sums of money on a awesome yet needless expensive and dangerous activity.
it isn't going anywhere, when you are actually living like an adult you will be free to follow your skydiving dreams.