While global income inequality has been decreasing for the past decades and billions were lifted out of extreme poverty (https://ourworldindata.org/global-economic-inequality#global-income-inequality-increased-for-2-centuries-and-is-now-falling), extreme incomes and extreme wealth by the Top 1% stayed stagnant over the past decades or has even been increasing in some countries (https://ourworldindata.org/grapher/share-of-top-1-in-pre-tax-national-income, https://ourworldindata.org/grapher/share-of-income-received-by-the-richest-1-of-the-population).
With people making millions or billions in income each year, more than the income of most people working their entire life and more than they could ever consciously spend, a new tax bracket for extreme wealth has to be established.
All yearly income above 1 million euro should get taxed higher than the previous tax rates, adjusted upwards into the multi-million range, and ending in extreme taxation for everything over 1 billion euro per year.
The taxation of extreme wealth should come combined with higher taxation on luxury goods (jets, yachts, jewelry), and secondary or tertiary homes which are not used for living but as an asset to store wealth while housing becomes unaffordable for the middle and lower class due to rising housing prices.
Hording absurd amounts of money should be disincentivized as well. Billions of euro sitting on a bank account not being used should get taxed by several percent each year. This is especially needed in the case of multinational corporations such as Apple, Google, and Microsoft, storing hundreds of billion dollars with no intent of using it.
The EU can become a leading example by creating policies unifying the tax standard of its member states and promoting stronger income equality.