Well, the whole thing is computer data, stored on media. Already these days it's hard to find hardware to read the 5.25" floppy disks that I stored my code on in the late 1980s, and that's just three decades. Preserving digital data is a continuous effort.
And yeah, you can encode your private keys in gold, and I kind of think that everyone should do that, to keep future archaeologists puzzled :-P
If your house burns down, there is a reasonable chance of recovering, eg, gold slag. Not so much chance of recovering the markings that were on that gold before.
It is difficult to compare the durability of gold and bitcoin. It does seem plausible, given the length of time we've been using it, that gold's value is completely related to its intrinsic properties and difficulty of mining.
Bitcoin can't possibly be valued on its intrinsic properties, because I can fork the entire technical edifice, start a new blockchain called it Bitcoin+1, and the fork will have no value vs the original.
And yeah, you can encode your private keys in gold, and I kind of think that everyone should do that, to keep future archaeologists puzzled :-P