It's definitely NOT a ponzi scheme.
I've literally invested $0 in buying steem, yet have made over $1,000 on posts and comments.
I've been here a week. The post that made me the most money was one where I told a whale he was sounding like a sociopath and encouraging a bad view of this place. I'm hardly a the type of person "go along to get along", or just say things because I think they'll pay off.
That said, what makes a ponzi a ponzi is that you are taking money from new investors to pay old investors. That's not the case here. Here new money is just made on an as needed basis and distributed as fairly as they think is possible to do so.
There is no transfer of wealth from old users to new users either. If the price of steem stops rising then the amount of steem in the system will continue to increase and it will push down the value of each steem in dollar terms. However you are not paid just in steem, you are paid in steem backed dollars. Ergo whether the price goes up or down your holdings are about as secure as anything can be in the crypto world.
Content becomes cash. Literally "a penny for your thoughts".
If you want to speculate that's fine it's your business but when you buy steem off the market it's steem someone earned and is selling.
I rage an piss and moan about a lot of things on this site. But the truth is, bitUSD & SBD are the smartest inventions in the cryptoworld ever in my opinion. People talk about Satoshi Nakamoto needing a nobel prize, but my nominee would be @Dan for this system. Flawed as it may be, it's still a damn site better than anything else going.
RE: Don't Buy Steem and Steem Dollars