Yes, It is a profitable business, but you must keep in mind that you should have a good number of followers and more traffic towards you. It is because, people want you to advertise their products to number of people. If you don't have a good source to get more traffic then how will you advertise their products?I have heard alot about starting up an advertising agency and how profitable it can be and I have seen some people who are doing well there also. I also want to know how it works and how profitable it can be.
So, it is profitable, but with the good traffic of followers only.