That implies a sincerity in their beliefs.

While it's difficult to figure out what people's true motivations are, the promotion of new cryptocurrencies, the "get in early" rhetoric, leads me to believe most cryptocurrencies are little more than pyramid schemes. The ability to mint/mine/farm currency without paying in directly doesn't really negate that since it is intended to become more difficult as time progresses. The actual value comes from speculative investments from a growing number of people.