Postdocs in biological/physical sciences are easily 3-6 years for < $60k (generally closer to $40-50k in the past 5 years), and the chances of getting an academic position with meaningful salary are very low. Postdocs are plentiful, positions are scarce.
Meanwhile the postdoc could have been making $100-120k for a profession where the job market is almost the polar opposite, which makes a difference for job security/stress. The 2x-4x salary difference, especially during the late 20s and early 30s, is a pretty big deal, especially if you're able to save that extra 2x-4x.
The even crappier pay in humanities makes it basically undoable except for the upper class or outsizedly talented. The low pay in science makes it doable for normal people, but there is a strong financial incentive not to.
Meanwhile the postdoc could have been making $100-120k for a profession where the job market is almost the polar opposite, which makes a difference for job security/stress. The 2x-4x salary difference, especially during the late 20s and early 30s, is a pretty big deal, especially if you're able to save that extra 2x-4x.
The even crappier pay in humanities makes it basically undoable except for the upper class or outsizedly talented. The low pay in science makes it doable for normal people, but there is a strong financial incentive not to.