Most of the gold 6102 collected was sitting in banks instead of people's hands. Probably few surrendered their gold and the state didn't knock door to door to seize it.

It is likely that for bitcoin the game that has been going on since Ross' days and intensified recently is to scare people enough so that they let go of it (e.g. linking bitcoin to financial crime, charge a few people for domestic terrorism...) and the ETFs buy all it can to centralize it. On a long enough timescale it is a serious threat because every time a bitcoiner spends there is a risk that the recipient sells it back to Blackrock, sucking everything like a blackhole