I find it absurd that a healthy percentage of people today support taking 70% of every dollar someone earns beyond $10 million. How is that possibly morally correct?

As I've asked before, where does it stop? Why is 70% the right number? If you're for something as crazy high as 70%, shouldn't you also be for a 90% tax rate, or perhaps even 99%?
There are good, generous, big-hearted rich people, and there are cold, greedy asshole rich guys who will exploit anyone or anything to make extra money.
There are way more cold, greedy rich assholes than good, generous, big-hearted rich people.

The US had a top rate that exceeded 90 percent through the 1950s and early 60s and a 70 percent top tax rate from 1971 through 1980. Then President Reagan got Congress to cut it to 50 percent starting in 1982.