I don't question that their income from what ever source should be (highly) taxed. However the wealth tax should be on top to fix the errors made in the past (and are currently made) leading to such accumulation of assets. The question is how should non-liquid wealth, such as estates, shares and bonds, be taxed.
Yes, but you also pay tax on everything else including housing and every day goods via Sales tax. And as a percentage of wealth I'm sure that adds up to way more than 4%
But my taxes as a percent of my wealth are probably closer to 20 percent (e.g. 20,000 in taxes on 100,000 in wealth), than the 2 percent suggested here.