In my opinion I think the reason why source of income is very important in bitcoin investment is because bitcoin investment is not like that of shitcoin investment that you will just put your money and start waiting for the value to get hype No" hyping does not take place in bitcoin investment Rather the amount you invested will determine how the potential return will look like, so for you to have a reasonable portion you need a source of getting money so that you can be able to make a large portfolio by investing weekly or monthly, though most people can only investment in bulk and then allow it to compound, but anyone who is going with this approach will not be term as bitcoin investors.