Those oligarchs won't be able to print more bitcoin or exclude (sanctions) their political enemies from conducting trade. Seems fairer than the current system.
Sure they would. If bitcoin continues to exist much longer, you'll likely see the larger governments define a set of rules for domestic miners, perhaps including requirements to only process transactions from registered accounts or signed by specific keys, or otherwise authenticated. Any international agreement on such a system reaching significant hash power would fork the ledger into legitimate and illegitimate versions, and generate obvious consequences
And even if they imprison you they won't be able to access your money:
https://amp.scmp.com/news/world/europe/article/3120852/germa...
It might be intractable to confiscate bitcoin by attacking the math, but why wouldn't governments just put people in jail until they pay up? With adequate control over the internet, governments would be fairly able to track who's transacting.
Moreover for the vast majority of people on earth would still have basically zero money relative to the emerging bitcoin oligarchs. It would be a grossly unequal society, where there would need to be some non-math-based approach to getting money from the wealthy to redistribute to the less fortunate.