> That is the whole point of bitcoin. There is no entity that can prevent you from using it.
This is a common marketing claim which doesn't hold up if you think about it even a little. It's like saying that no entity can prevent you from saying something because you define “prevent” as whether there's a cop following you around ready to punch you if you open your mouth — almost all real-world censorship happens after the fact or relying on third-parties, and Bitcoin is no different in that regard.
Bitcoin can trivially be blocked or tracked at the network level. If you have a hostile government, consider the risks of connecting to a well-known network if they've banned it.
If Bitcoin is not completely banned, a government can require everyone to report transactions for taxation or other purposes. That means that your ability to evade punishment for a transaction comes down to whether all of your earning and spending can be done outside of the country without leaving a trace of that network activity, and that you and everyone you make transactions with will never be compromised (think about how would you know?) or cooperate with the authorities (businesses will share their records because they have a legal presence which can't ignore local laws). Similarly, if you want to actually spend that money you have to be extremely stealthy to avoid the authorities wondering how you're spending more money than you appear to make, hope that someone you know never develops a grudge or is coerced to tell the authorities that you're, say, living lavishly on your trips outside the country, etc.
If _any_ of those points aren't true for you, Bitcoin is not safe to use — especially because the public ledger gives the authorities a huge data source of all of your historic activity so you have to consider not just whether they're watching you at the time of an illicit transaction (as is the case with cash) but also whether you or the the other party will at any point in the future have your wallet IDs leaked.
(Yes, I've heard of tumblers. Ask yourself who in this situation is going to risk being charged as an accomplice to the worst crime anyone else using that tumbler is involved with — or whether the police are running the tumbler to get criminals to self-identify their intent to do something illicit.)
The underlying concept to understand here is that sovereign states control their territory. If you live under an abusive government, you are only safe to evade their rules to the extent that the government is weak — if so, just use USD like everyone else. If not, all of the options are risky and there's no magical thinking about technology which is going to materially change that … but almost all of it opens up new avenues for fatal mistakes which are hard to recognize until after the fact.