PhD is a really big investment. You are spending 4-6 years of your prime earning years chasing a dream or in the hope of making a dent in your domain’s problems.

All that while your age mates from school/college/town are progressing in their life and career.

Also if you get into non-academic job then those early years foregone usually have disproportionately bigger impact on your career progression and your accumulated wealth.

The decision is really big one and it’s only natural to consider money angle. I’ve known quite a few get into it because of interest and then getting disillusioned as they watch the world pass them by.