Yes I understand that. Plundering the wealth of the rich is a terrible idea. It's a classic straw man:
Theory: We should tax the rich.
Straw-man: If we took the 400 richest people it would only fund the gov't for 7 months!
Accept Fallacy: Oh, then taxing the rich won't work!
Reject Fallacy: Ok, but there are more than 400 rich people, and no one is saying abolish taxes on everyone else. So perhaps there is a better balance, where those with incomes a certain multiple of local medians pay a higher progressive tax rate.
What I pointed out above was just the weird cutoff of 400 to arrive at 7 months. Why not a base 10? 100,1000,10000 richest. Or something like "The richest 674 people in America could fund it for 1 year" (made up numbers). When an arbitrary number is selected, I just get skeptical. Especially when it anchors to nothing else. What metric/group/club is there that top 400 American billionaires make up. Why do I care about 7 months?