A Doctor of Philosophy of the University of Oxford in full academic dress. A Doctor of Philosophy degree (often abbreviated Ph.D. , PhD, D.Phil. , or DPhil) or a Doctorate of Philosophy, from the Latin Doctor Philosophiae, is a type of doctorate awarded by universities in many countries.
However, independent expenditures are often used to work around campaign contribution limitations, so a candidate may appear to have a strong outside support network when the money isn't really independently spent but rather provided by people working in concert with the primary campaign committee. References.
I think that it is a very conservative requirement for financial independence as it assumes: You will never receive anymore money (no state pensions, salaries, inheritance, profitable hobbies) The amount you spend stays the same. In reality most people spend less as they age.