Mania or bubble. I don't consider crypto market overall to be any type of scam or scheme. Just like I don't consider stock, or housing market to be one. Even if there is insanity, scams, schemes and fraud inside all of them.
At least in theory, stocks and housing are underpinned by intrinsic assets (i.e. things that exist in the real world and/or intersubjective agreements whose value and status are enforced by people with guns). Crypto doesn't have that quality even hypothetically (except to the extent that people insist it does), which pushes it toward the same category as many of the well-known financial scams (which were characterized by people obscuring the lack of assets propping up the value of the scheme).
Edit: I was being overly general with the term "pyramid scheme"
I would only use pyramid scheme to mean rather specific structures. Like many MLMs are, where revenue and profit for individuals is generated by their recruitment activities and so-on. Not in general getting more people in a bubble. Just like Ponzi is centralized system where central actor pays out to old investors with new investors money. Not an open market where anyone can enter and leave at any time.
You keep using the word trustless, but Bitcoin is at best no more trustless than any other currency. You are falsely equating your balance not being able to be arbitrarily changed with it's value being stable. Only the latter (spending power) matters for a currency.
Bitcoin requires you to trust at least three things:
Others will exchange it with you.
Governments will not make holding/using it illegal.
It will not lose it's value overnight. There is absolutely no reason to believe these will continue to be true.
Edit: I was being overly general with the term "pyramid scheme"