During my time in a computer science PhD program at an American university (2003-2010), my stipend maxed out at $23k a year. That was not competitive compared to having a normal job, nor would I have felt comfortable supporting anyone else.

Adjuncts professors teach at American universities on a course-by-course contract basis. These people usually have PhDs. Some would like tenure track positions. But it’s generally a career dead-end.

I suspect your experience is from Europe, and I don’t think it generalizes to the US.