[lxgr]

Regulations prohibiting possession or trade, for example.

If you think this is very unlikely to happen, it's worth remembering that this has happened with gold in the past, in the US.

[toenail]

We've already seen what happens when there are legal hurdles, activities move to other countries, or people find legal loopholes. This has already happened a few times, and bitcoin is doing just fine.

[lxgr]

Sure, but does that matter if you have to sell to the government, possibly at a rate lower than what you bought it for?

[toenail]

Doesn't matter to me as I'd just leave the country.