Scam? Ponzi? Meh... a bit harsh there.
Read this to see how it all started and judge from the beginning: https://steemit.com/steem/@joseph/the-history-of-steem-steemit-launch-in-the-words-of-dan-larimer-from-the-early-launch-days
It's a beta work in progress.
I have invested $300 of BTC at first to get a jump on SP, but it's not much, I have earned way more than I paid into. I've only been here a month so far. I have had success, how? Because I actually create real meaningful high quality content to change ourselves and the world, and it gets recognized as such.
It's not free easy money. You have to actually create valuable content. Otherwise, yeah, you can moan about how unfair it is, and it is in a certain sense. But that's life. Don;t expect a free lunch anywhere. The people who got in early and are still here, want to keep what they have, for sure. Maybe more changes are coming to make things easier for people to get recognized, maybe not. I don't view it as a ponzi. Other crypto's are. This is currency is backed by something real: content that exists, not just mined coins with nothing behind it.
For those who are patient, work the platform, and buy low this time, when it skyrockets in success in months or years, they will reap the rewards of buying low and selling high.
Take care. Peace.