Generally people participating in a Ponzi scheme do not view it as such. The tactics deployed by truly oppressive regimes make anything easy to confiscate including bitcoin.
But they have to know someone holds it in the first place. You can walk around with a seed phrase in your head and no one would know.
They aren't going to immediately execute everyone who is crossing the border. Even in authoritarian regimes, some people may be able to leave, and borders are not completely shutdown.
And in that situation, for those people, it is useful to be able to carry money, in a way where they do not know that you have it.
I think you fail to understand the power of a true authoritarian government, particularly if they can monitor and limit your access to the outside world.
* Use a VPN, you're guilty of Treason.
* Use a currency other than the North Korean won, you're guilty of treason.
* Use an electronic device other than state sponsored devices, you're guilty of treason.
All executions will be recorded for posterity and broadcast to the people as a reminder of the power of the state.
However, as soon as they start doing that to the first few people, what's going to stop everyone else from instantly sending their bitcoin to family and friends across the border for safe keeping?
With wealth like gold, land, oil, or any other physical resources, an oppressive regime can just kill all dissenters and take control of everything. The payoff to violence is huge.
But with a digital wealth like bitcoin, which can flee the country at the speed of light, even if the owners can't go with it, the payoff to violence evaporates. The oppressive regime that spends a lot of time and energy torturing and killing people will have no spoils to show for it.
The only wealth people could offer for Bitcoin is wealth in a country with an oppressive regime. Who internationally can even take possession of that to cover their expenses?
The only plausible option would be to actually just setup a mining rig and mine the Bitcoin, since presumably for a while their might be an electricity grid their and the BTC network ascribes value to that activity...except you can't mine on commodity hardware to anymore either.