A source of income is something that provides you a steady stream and flow of money, either on a weekly, daily or monthly basis, and for something like Bitcoin, you cannot consider it a source of income because you have to invest in it to actually profit from it so Bitcoin is actually more of an investment opportunity or a currency than it is a source of income. If the plan of someone is to regularly make withdrawals from their bitcoin to support their lifestyle and livelihood, those kind of people will find it difficult to really hold or keep any Bitcoin as an investment for the future.