@jlou Under the gold standard for consent, it is specific, informed and reversible. Self-sale and coverture require one to unconditionally give away all rights forever: not specific, informed or reversible. They cannot be validly consented to.
Even supposing the argument against the sale of voting rights failed, it is only concentration of power that creates the mutual incentives for such a sale. Economic egalitarianism = the sale ceases to be mutually beneficial even if morally permissible.