If the distribution is such that the gap between the rich and the poor is increasing
The thing is that there will be only a very few 'rich' and many will sell along the way while the lower mass keeps growing.
I mean Haejin is basically earning a dolphin account every month and he is not the only one.
There are a couple but it is unlikely there will ever be many more. While more people come in and earn, the lower mass of SP grows while the upper end loses percentage draw on the pool.
Not quite what you are after but hints at it.
https://steemit.com/busy/@taskmaster4450/steem-whales-are-losing-their-power-the-system-is-not-broken-report-through-3-31-19