Which category of clients do you always target as freelancers?

[Btaliat]

In order to build brands easily, some freelancers always target only categories of people. This will make it easier for them to know more about what those categories of people want. For instance, some freelancers only focus students. They write for students, do assignments for them and any other needs that the students may need. In fact, if other people, aside need the same service, they may not accept the offer. Is there any implication of this?