If it’s a tax on holdings applied every year, 5% is significant. It’s best compared with property taxes, which is another tax which works in a similar way. Property taxes are often capped at 1% of assessed value.

I’m in favor of taxing the rich, and taxing their holdings at 5% (without too many loopholes) would exceed my expectations. I expect this to get whittled down to around 1% before actually making it into law, though.