I don't deny that cryptocurrencies might play a huge role in the future. And algorithms are indeed pretty clever. But I don't see why that prevent current bitcoin implementation to be a pyramid scheme and thus I ask. And haven't been answered so far.

It's like arguing that tulips madness wasn't a buble because tulip are beautifull and still sells today. Evrything can be used by speculators to build a buble, even rice or corn (and that's even worse than bitcoin because lots of people don't eat as much as needed as of today).