The question is more for those who once converted a lot of bitcoins into fiat to their bank accounts
How did you do it so that the tax authorities and the bank manager would not question where the money came from?
The best means to achieve this successfully is in doing it through a decentralized p2p exchange, but making use of a centralized exchange is not ideal enough for us to be able to achieve maximum privacy or evade government regulations, you don't have to specify on the information on your transaction to be crypto transaction in other for you not to be announcing yourself its such you're doing,
The thing is that many years ago i bought my bitcoins from a person in cash and he transferred them to me in my presence
How can i make sure that this money is transferred to my bank card without any problems?
It is not difficult to achieve, if you want to make physical p2p transaction, then i will advise that you make use of an escrow service provider that us reliable, while the online one is the decentralized exchange i have to recommend.