To tax the rich is not the same as disincentivizing investment! Investment matters to the economy, not capital.
Yes you need capital in order to invest. You need the right amount of capital in the right places! Rich hoarders are not the best investors.
If you want to tax the rich without taxing capital or labor, then you want to tax land. Unlike capital, there is only a finite supply of land and it cannot be moved overseas. Wealthy individuals like owning land in areas with high land values in stable countries with high public spending, and with a land value tax they directly pay for it.