If it is too easy to gather wealth so you can gather wealth without actually having to create any value (through corruption, extortion, monopoly, theft, deception, enslavement, etc.) then you will have the bad kind of inequality where most people are not compelled to put hard work to create value for others in order to create wealth for themselves.

Again, GINI does not differentiate between the good and the bad kind of inequality, so two countries with same GDP and same GINI might be very different. One may be on the rise, with a number of enterpreneurs creating huge progress and value and the other might have couple of oligarchs who were able to amass their wealth with corruption.