correction... always were worthless.
It's always been a con game.
Their so-called "value" was always determined by the ability of the person shilling it to make up bullshit. Literally the definition of a "confidence" game. Same problem as crypto in general. It's only has value if you have confidence in the person shilling it. The moment that person loses the confidence of their marks, the entire thing crumbles to nothing because it isn't backed by any real tangible assets.