That's largely true for an undergrad degree. For a graduate degree, and a PhD in particular, there aren't a lot of alternative employment options. I've been told that having a PhD in those fields makes you less employable for positions in general (because why are you applying for this job, and it is uncomfortable to hire an older person with a PhD for an entry-level position).
An unqualified 30 year old going for a grad position will face the same age bias regardless of whether there was a phd in their past or just 6 years of working in ski chalets.
