For current users:

We only have 50k active users on STEEM right now with a lot of them ( it seems) from 3rd world countries who are more than content making 1-2 $ a day on this platform. That has a momentum of it's own but that is certainly not the investor class.

For future: ( mostly my speculation)
As we get more content creators on-board ( OC types and Youtube celebs) they bring their audience with them and they stand to gain a lot of STEEM and rival the stakes of 1st gen STEEM investors. That gives me hope that SP will be more distributed in coming few years.
Our home grown Steemit stars mostly (not all) tend to be Investor class , which leads to not original content ( or original but creepy..whose name shall not be mentioned) in the trending section.