It's okay to be ignorant about how weird things work, but sharing opinions about things you don't know about should be avoided. A PhD "student" isn't really a student. They're an employed researcher at a research institution, working under more senior researchers who are able to attract grant money.
To use an analogy to the trades, the PhD students are the apprentices, the senior researchers / professors are the journeymen. Do not misunderstand, the PhD students are doing labor for the benefit of the university, and getting paid to do so. The problem arises from uninformed people who ask exactly your question, operating on the misguided assumption that graduate school is just more, harder undergraduate school.
To use an analogy to the trades, the PhD students are the apprentices, the senior researchers / professors are the journeymen. Do not misunderstand, the PhD students are doing labor for the benefit of the university, and getting paid to do so. The problem arises from uninformed people who ask exactly your question, operating on the misguided assumption that graduate school is just more, harder undergraduate school.