> The problem with this comparison is that choice of size of the wealthiest share of population (top 110, top 400)

I found it fitting because it's pretty close to the same percentage of total population in either case (1 in a million)

> Why won't we all just refer to good old Gini coefficient and call it a day.

Although you can use Gini for wealth, the "usual" Gini coefficient is income.