Hackers and others have been sending messages about Steem being a Ponzi Scheme. Here's why it's not:
A ponzi requires you to pay to feed the system. Steem is free, you don't have to buy if you don't want.
Is there a pyramidal structure ? Right now yes somehow. Without the upvote of a whale or a dolphin, your post will be forgotten in 10 minutes because of the extreme concentration of steem power in a few hands and because of the structure of the site. I said it in a previous post about dropdown menu here: There's a "dark steem" where the majority of posts are forgotten. Usually after 10 minutes, you disappear from the first page of new (since update 0.8 curation rewards are more interesting after 15-30 minutes, making it happens often). And then if it's not active or upvoted fast enough, it's not on the radar anymore until payout time. A good tag can help a little but still your best chance to get anything is a whale/dolphin upvote.
Can simple users with their 5 steem power make post more visible? No. I have seen posts with 30 upvotes at 0.1$.
That's why it's a pyramidal co-option structure, if a whale founder upvote you (+1000-2000$), you get enough steem power to become a minnow/dolphins instantly otherwise you never get anything unless you buy Steem on exchanges. Then you're free to vote for who you want and create minnows.
Will it change in the future ? We can hope that it will, if the interests generated by the already owned Steempower are lower than the wealth spread through upvotes. With time the wealth will spread through upvotes and mining but it can be slow.
How to make it faster ?
-Lower the difference of weight in votes
-Create mecanisms to spread the wealth to more blogger
-Make others not trendy posts more visible like proposed here
Steem must not become a giant clickbait trap ruled by a small oligarchy. We can find solutions!