You have done a much needed research about the prevailing inequalities on this platform. I think the holding of large SP is not so bad if it is not used for self voting or mutual voting. Problem lies with the reward distribution system. Some users are raping the reward pool. One such person is able to secure almost 2% of the whole reward pool for himself! Also, some others are busy in downvoting minnows and upvoting self posts and comments.
You rightly stated that if steem were a country it would be the most unequal society in the world. In this unequal society only bid-bots are real winner. They are paid for upvoting and they also receive curation reward. So, their owners are amassing a huge wealth for themselves and leaving other to feed on crumbs.
Developers will have to amend this system otherwise, this platform will not survive a long.