Except CS, or if you an international Olympiad champion, PhD is a bad idea across the board. Even if someone thinks they want to do a PhD, its better to work for a few years to understand market forces so they can do a thesis that is not fully removed from reality. This medium blog post from economist is a worthy read
Keep in mind that the system is also slightly different overseas.
In many non-European, non American countries, a PhD is three years after your undergraduate (with honors year, 4 year undergraduate instead of the normal three).
https://medium.economist.com/why-doing-a-phd-is-often-a-wast...