* Field of study: PhDs in fields like engineering, medicine, and some areas of finance often command significantly higher salaries than bachelor's degrees in any field. However, a bachelor's degree in a high-demand field like software engineering might earn more than a PhD in a less lucrative field like history.
* Experience: A person with a bachelor's degree and many years of experience in a high-paying field might earn more than someone with a recent PhD.
* Specific Job: The specific job title and responsibilities play a large role.
* Location: Salaries vary geographically.
* Industry: Some industries pay more than others, regardless of degree level.
In short, while a PhD *generally* leads to higher earning potential, it's not a guaranteed higher salary than someone with a bachelor's degree. The comparison depends heavily on the context.