Are those PhDs being paid with a decent salary? If not, I can’t agree with your statement. PS. I did my PhD in an EU country where it’s treated as another researcher job with salary and benefits

PhD candidates in the US usually get somewhere between $25K and $50K stipend, also some level of benefits (typically health care). Sometimes there is a tuition waiver (student does not need to pay grad program tuition).

In my case I was making $32K/year with a tuition waiver and health benefits around ~2000, in SF, which was barely enough to rent a shared apartment and eat food. The only way I could rationalize it is that I was maximizing my future freedom (job choice).