It comes down to supply versus demand. If what somebody learns in increasingly advanced education has any practical benefit then it would imply that they would

It comes down to supply versus demand. If what somebody learns in increasingly advanced education has any practical benefit then it would imply that they would have a practical skill that few other people would have. Of course this is premised on the rarity of supply, which is no longer really true with millions of phds and growing out there. And it's also premised on the existence of a practical and meaningfully valuable skillset gained in the process of obtaining the doctorate which is I think reasonable, but still certainly debatable -- and at the minimum going to be contingent on what/where somebody studies.