Three reasons:

1. Gold, like bitcoin, is hard money. It's value is not based on the decree of any government. No matter what happens, you end up with some gold and some bitcoin.

2. You can buy and warehouse gold at a reputable vault in any stable jurisdiction. Bank accounts are always subject to counter-party risk and even treasuries could be "frozen" by the US govt if they decided they didn't like the entity holding them.

3. If you consider fiat currency to be the cause of all debasement and debauchery that has wrecked modern society, holding it as a (significant) asset is a moral dilemma.

BONUS: Gold is the asset by which central banks defend their currencies, buying up their gold away from them is accelerating their demise.