yes, you can make constant earning through bitcoin trading. you must aware of daily updates and current market trend of bitcoin.
With bitcoin trade it is not easy to get a monthly fixed income. You may lose money due to factors that are not in your control. Especially if you are doing margin trade, you have to be very careful. It is possible to lose everything in your hand.
That's right its impossible to expect a fixed ans stable income from trading as it will be always changing depending on the profit and loss that you make and even if you are into majority times still you cannot come to a fixed income as your profits will be volatile depending on your capital.
Yes, Fixed income is not at all possible with trading because sometimes you may loose and sometimes you may make profits. But it depends on the coin that you choose and also your return will be based on investments also.