Are there really only Bitcoin, gold, and land that meet the following three elements?
First, scarcity—they cannot be arbitrarily increased.
Second, they cannot be tampered with.
Third, they must be sustainable over the long term—they do not rely on the credit of any government or institution.
However, this security against the so-called dark ages appears to be only financial. In the face of war or sovereign attacks, these three assets would be powerless and could even be easily plundered, especially land.