I am not sure I follow the logic. Bitcoin becomes "bigger" when there are more big actors not using it but just hoarding it? And thus less volatile - until one of these big actors decide to dump their holdings to the thin market used to trade only scraps left from these big actors... Sorry, not convincing.

The idea is that bitcoin is something you prefer over fiat currency in your bank account. The same idea that gold bugs have.

If that's the case, then bitcoin owners will only dump their holdings if a) they fear that the bitcoin network is about to collapse for some reason or b) they need to put the value stored in those bitcoins to use.