This question is important, especially for people of modest income that SUDDENLY start to make huge profits from crypto-currency.
I understand this because it might look suspicious that the holder of the account is into in bad business like fraud, rubbery etc but the solution is to start to transfer money to the account gradually and with time bigger amount can be transferred to the account. With this way, it won't be an issue but if large some enters at once, questions will be asked.
I understand your point, which is very practical, but sometimes it may not be feasible to transfer small amounts slowly.
This is because the crypto market is very volatile, crypto-exchanges might have sudden cash flow issues that prevent withdrawals over a period of time.
I would love to pop into my Local Bank branch (in the United Kingdom) to tell them that I am into crypto, but I am a local person in the area - I do not want to attract attention to myself (or to attract potential thieves), because we do not really know who these Bank staff really are, or if they have connections to the criminal underworld.
I do not want to turn myself into a local target.