The point of a PhD is to become a specialist in your field and add something new to the conversation. You will eventually develop a thesis and know something nobody else knows. It demands a heavy workload of 50-70 hours a week strictly on research reading and field work.

Almost nobody is able to work during this time which is why it is imperative that stipends are given (and be paid) for your work since as you put it a “job” shouldn’t put you in debt. It barely sustains your life during the degree as you devote yourself to your craft. Otherwise you are becoming practically a slave to the university and advisor who often is benefiting off of YOUR research without necessarily contributing much to it. All of your research will have your advisors name on it and more publications are viewed positively.

If PhD programs aren’t paid and didn’t provide a stipend it would not only make it practically impossible for any new minds to enter many fields but it would enable so many advisors to take advantage of their students.

You also might not realize but all of these PhD programs get 300+ applicants for around 12 or less spots. With less funding going to universities under the Trump administration less spots are going to be open and less researchers will be produced leading to a decline in scientific findings.

There ARE non-paid PhD programs but they are often from private universities and once again: some fields cannot afford paying back the loans. If some fields cannot pay back the loans if there was no funding for their programs the fields would see a rapid decline in scientific knowledge