It is not unusual, from reading the literature of that profession, for clients to feel all sorts of ways, including jealous of the therapist's other clients. I don't think the OP said anything to imply they meant the therapist could or should not be hired by other clients. I don't understand about 99% of why, what and how people say they do therapy - almost no one seems to understand how or why I do it - but I consider that lack of understanding to be the lacker's problem, not the one doing therapy the way they are doing it

I never see other clients. I don't care about them. I don't like therapy or the therapist enough to think about the other people who hire her