As a matter of fact, Bitcoin is already a source of income. That is the major reason why most of us is in here, bitcointalk.org. We want to engage in signature campaigns in order to earn bitcoin, thus our source of income. Many are engaged in trading, investment, gambling and all are aiming to earn bitcoin. However, it is not very advisable that this will be our major source of income. An alternative source of income will be better since bitcoin is very unpredictable.