Warning Signs of A Ponzi:
The following set of rules are the classic warning signs of a Ponzi.
Unclear Business model with a lot of smoke and mirrors where the business withholds information on profits and how the business is run.
The developer of Steemit was also the developer of BTS, which he seems to have completely abandoned. The whitepaper is 44 pages long which means that everything is made overly complicated, for reference: the Bitcoin whitepaper is 10 pages long and that changed the world. I can also not find any business structure behind Steemit.
Aggressive sales techniques that use testimonies of others who got incredible returns on their money with no other substance.
Aggressive sales technique can be argued. I did find testimonies below. What is not up for argument is the incredible returns. 2-3 line posts can get over 1,000 usd which makes no sense and is obviously unsustainable.
Investment opportunities that asks you to spread the word and bring in more investors
Well this one is obvious, just look on Twitter/Reddit and other social media, this is being heavily marketed to make the price go up and it's in an obvious bubble.
If it sounds too good to be true... it is. You can't generate double digit returns year after year regardless of how the market is doing.
The first part is obvious, it is too good to be true. Some people who write 10 min blog posts getting 10,000 usd or more is literally insane. The last part was probably written before crypto.
If you are promised guaranteed returns. There is a risk with any investment and that should be made clear.
You are promised guaranteed returns. The idea is that you put as much Steemit in your Steemit account and get guaranteed returns. However noone takes into account the price of Steemit on the exchanges which could crash really hard. Then everyone who invested and was promised guaranteed returns is still getting burned hard.
If you feel bullied when you ask too many questions.
Try to ask the dev some questions, he is known in all of crypto as very aggressive, hostile and uncooperative. One example was only releasing a Linux wallet saying that Windows was for losers.
Stalling when you ask to withdraw funds.
This is the most important one. Your Steem is locked, you can request a bit every 7 days but only about 1% worth. This is a huge issue, it means it takes you 2 years to cash out. In crypto 2 years equals 20 years in normal life. The whole crypto landscape could be different.
Conclusion:
I will not make a conclusion for you but make your own conclusion. If you've been in crypto long enough you know that if something looks like its too good to be true, it always is.