Gregory's Server@phneutral … and there we are at two core problem with the petition: a lack of understanding/knowledge of the tax system and a lack of definition what (ultra) rich people are. As following the discussion, I found a variety of opinions of who is addressed by „the rich“.
Like in the post to which I answered, where only highly wealthy people own stocks and / real estate. If that is the belief system the petition is driven by, it has a taste of envy and misses the goal completely.
@Konafets @mina the proposal is quite detailed imho. Oxfam state on their German campaign website: „Für Deutschland schlagen wir folgendes Steuer-Modell vor: Zwei Prozent auf Vermögen von über fünf Mio. US-Dollar (ca. 4,6 Mio. Euro), drei Prozent auf Vermögen von über 50 Millionen US-Dollar (ca. 46 Mio. Euro) und fünf Prozent für Vermögen, die eine Milliarde US-Dollar übersteigen.“ https://aktion.oxfam.de/tax-the-rich