The minnows would most likely self-vote, right? As those minnows become whales, would they act any differently than current whales? By that, I mean it may not be the size of someone's wallet that matters but who they are as a person. We'd probably see the same level of greed and generosity in both minnows and whales. In fact, I wouldn't be surprised to see more generosity in whales because they mostly understand how benefitting others increases your own wealth. Whales, to me, aren't immediately bad by default. If their votes and actions are overly selfish, I can see that's not helpful. But, could it just be a matter of perspective? If I get one person to give me $1 for an exchange of value is that fundamentally different than getting a million people to do it?
A day without whales sounds quite interesting, but I'm not sure it would effectively solve the concerns you have.