Are they wrong?
The other person in this relationship is usually called an acquaintance. They are in your life only because it is convenient. You don't really trust them but that does not limit how they can benefit you. You can have this type of relationship in your personal and professional life. I think it is a must in your professional life but it can be shady in your personal life.
When is it considered using the person? Is it only considered using a person if they are helping you with a service you could pay for? (That logic doesn't really work because now a days you can pay for anything.)
I have had some relationships of convenience. Some of them I felt guilty about others I did not. Everyone you deal with is not your friend or enemy. A lot of people fit into that area between. They are neither friend or foe, just there for the moment.
