Well, it's not a ponzi scheme. It's a MLM/pyramid style scheme. The idea over the long term is that there are more future investors than past investors and therefore there will be more money in the future than in the past. However, returns only last until growth limits have been reached. The problem is that everyone who buys Bitcoin wants those gains but they are exclusionary/rivalrous by definition.
By that definition any stock that doesn't pay a dividend is a pyramid scheme. Of course, if you believe it has no value whatsoever, then anything can be seen as a pyramid scheme.
I was going to make a similar comparison. I casually invest and trade crypto and stocks, I have been burnt when early adopters sell off after a company releases a good announcement. After a good announcement, new investors will buy and early investors sell off at their expense, I've seen this result in a stock losing more than 40-50% of it's price, sometimes it will never recover. I think both markets are affected by similar forces.
