I used that number since that was the number the parent comment saw as being obviously too much already, so I didn't need to use a higher number.

I do think 0.1% would already be pretty appreciable. That's already several 10s of billions a year. The current budget for all of the IRS is on the order of 10s of billions now, so I really doubt adding that new tax would be a net-loss.

And, of course, once you have a wealth tax and the sky doesn't fall, tweaking the number up over time is easier.