I am not commenting on what you should or shouldn't do. (I didn't see anything "unreasonable").

My thinking is on the question of where the motivation should come from. The motivation "or rules" shouldn't appear to come from you.

Access to large amounts of money comes with inherent responsibilities.
The child (or adult) that violates these responsibilities looses their "rights."

This is how the world works.

You didn't make the rules.