So in the scenario where people in most countries hold some of their assets in crypto, when a nasty regime starts rearing its ugly head there are a lot of precautionary steps they can take--they can put more assets into crypto, and they can shard their keys and give the shards to friends and relatives outside of the country （or just send the crypto directly to those people, since bank freezes don't work on Bitcoin.) Importantly, having an asset that they can store on a single scrap of paper (or literally as 12-24 words in their head) they can LEAVE earlier. Even gold is pretty tricky to leave with large quantities of, but crypto is by design the world's most portable asset.
So the wallets can't be seized and emptied, because the wallets are invisible and can't be searched for, and doesn't need to be stored with an intermediary at all. And the private keys don't have to die with the owners, because unlike larger quantities of gold, they can be transmitted to children or whoever with extreme ease.
I hope, but am less sure, that the mere existence of such an asset makes seizure less appealing to fascist regimes, because it's an order of magnitude harder than knocking on the door of a bank and saying "turn over all the jewish account records please" but I'm not relying on that being the case for this to be beneficial--crypto is truly designed for this kind of adversarial scenario!