That's not true. In some cantons, the very rich get extra deals, called Lump-sum tax, independently of their revenues. E.g. the Ikea founder only paid around 165000$ in total taxes in 2014 on a fortune of 46.5 billion US $ and all his revenues which he had.
Source: https://www.20min.ch/story/so-wenig-steuern-zahlte-der-ikea-...)