The logic of your argument is sound. And as a socialist, I’m with you on the need for the state to identify where it can most effectively extract and redistribute wealth for the betterment of all.
However, for me, a socialist economic policy should try to move with, not against, human nature. Asking a parent not to give all they can to their child (especially after their death, when they are not longer able to offer direct support) will always be difficult for people to accept.
So, on this, I cannot agree.