it is possible to get income here.
I think it is similar between Crypto and real Exchange,
it is possible to have real income but crypto volatility seems unpredictable, dont fixed a number,
just do it, earn it.
Bitcoin traders earning more than a 200$ as a profit per week. So it's not to fix in a number. It will vary every month. But I suggest you to do trading independent ,so only you will not sell when the price is low.If you depend on monthly income means,you need to sell when the price is low or high at the day one.If you not depend means,you will not sell when the price is low on day one.
It will only depend on how the person playing needs their money or not. Sell at high prices and buy at low prices