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.