Unfortunately, your definition is wrong. You are describing a "pyramid scheme".
A ponzi scheme is investment fraud. The operator pretends to invest the victim's money, but actually just keeps it. Generally, the operator maintains the fraud by using the victim's own money to pay out "profits".
Bitcoin cannot be a ponzi scheme because:
1. There is no operator.
2. Bitcoin is 100% transparent.
Ponzi scheme and networking we're all using cryptocurrency as their payment or reward method. They make it more appealing to people they wanted to join to make them look smart explaining bitcoin as decentralised, not prone to scam so on and so on. Those who really didn't study bitcoin or blockchain will be victimised as some were too good in bluffing and making stories, in my country, these schemes were both mixed telling investing their money in an investment and they will get reward when they get more referral as their downline. Bitcoin will never be a ponzi schemes we just hope they do their research in investing.