The truth is that Bitcoin *is* a Ponzi scheme. At-least until now.
It seems you don't understand what a Ponzi scheme is.
People who get in early and HODL will make way more money than those who come in later and HODL and so on and so forth.
Yet plenty of the people who go in early also sold early and made very little profits, and plenty of people who got in later traded well and made lots more profits.
The only way it will shoot up in price is if more and more people get into crypto and buy more and more of Bitcoin.
Not at all. If everyone decided to stop selling at the current prices, then the price would immediately shoot way up, regardless of whether or not any new people or new money got involved.
If nobody ever buys another BTC, the price will collapse
While true, this has nothing to do with whether or not Bitcoin is a Ponzi. If nobody ever bought another ounce of gold, then the price of gold would collapse. If nobody ever bought another bag of flour, then the price of flour would collapse. Doesn't make those things Ponzis.