While Bitcoin was not originally designed to be a pyramid scheme, it is very much one now. Nearly every other cryptocurrency was designed to be one from the start.
The trick lies in encouraging people to buy a cryptocurrency. Whoever is telling you that their favourite cryptocurrency is the real deal, the solution to all problems, probably is holding quite a bit of that currency, and is waiting for it to appreciate in value so that they can 'cash out' and turn a profit. The way to make that value appreciation happen, is by trying to convince people like you to 'invest' or 'get in' on it. If you buy the cryptocurrency, that will drive up the price. If a lot of people buy the cryptocurrency, that will drive up the price a lot.
The more hype you can create for a cryptocurrency, the more profit potential there is in it, because more people will 'buy in' and drive up the price before you cash out. This is why there are flashy websites for cryptocurrencies promising the world and revolutionary technology, this is why people on Twitter follow you around incessantly spamming your replies with their favourite cryptocurrency, this is why people take out billboards to advertise the currency. It's a pump-and-dump stock.
This is also the reason why proponents of cryptocurrencies are always so mysterious about how it works, invoking jargon and telling you how much complicated work 'the team' has done on it. The goal is to make you believe that 'there must be something to it' for long enough that you will buy in and they can sell off. By the time you figure out it was all just smoke and mirrors, they're long gone with their profits.
And then the only choice to recoup your investment is for you to hype it up and try to replicate the rise in value. Like a pyramid scheme.