Thanks for the response. I just read about Bitcoin mixer. It's an easy idea, but I guess its implementation is complicated. How much is the fee for it?
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Do you think governments will forbid anonymous transactions? For example, by forcing exchanges not to accept them.
Coinjoin is very weak. Read about coinjoin sudoku.
Exchanges are nice but not necessary. There will always be variation between jurisdictions anyhow, and crypto is global.