These kind of "what if everybody did exactly the same thing" type thought experiments are not really relevant for anything. If you had some Bitcoin 10 years ago

These kind of "what if everybody did exactly the same thing" type thought experiments are not really relevant for anything. If you had some Bitcoin 10 years ago, and you decided to sell/hold/whatever, that has almost no bearing on what other people would have done. The scenario where literally everybody holds and nobody trades is not a realistic scenario and not a particularly interesting thought experiment.