If the amount that they can give is more than an average voter can afford, it's an undemocratic and unethical system right away. It violates the fundamental principle of one person, one vote. It's like saying if a person doesn't have as much time to volunteer for a party, they should have more votes on election day, a whole bunch more. We would never allow that. Why would we allow it with money?
On October 5th, 2017. See this statement in context.