When you say “give up their millions”, how much are you saying they should be allowed to keep? Are you saying anyone with $2 million or more should be forced to give to those who don’t?
You’re assuming the person has $40 million in liquid assets and doesn’t plan to leave any to posterity. They probably made sacrifices to get that rich, staring out working 4 jobs, barely making ends meet but got out of it by saving up, investing, doing without non essentials, etc. Now, how do you know the poor person barely making ends meet isn’t in that situation because they squander their money on non necessities, gambling, drugs, etc?
Shouldn’t the rich be able to decide who they give money to? The government shouldn’t decide who has more money than they need and who needs it more, playing Robin Hood.
Who are you to decide who doesn’t need half as much money as they have?