It's not that the tech itself is a scam per se (although there are plenty of cryptocurrencies that were started with the express purpose of being a ponzi scheme or a pre-mined vehicle for a pump and dump).

It's just that widely available, totally unregulated financial instruments will always be primarily used to run ponzi schemes, pump and dumps and meaningless speculation (meaningless in that speculators are largely just speculating based on what other speculators might do).