Many fields now have postdocs but that's another 3-5 years, during which you'll make $50k/year, have limited job security, and may need to move. If your research works out well (good results, hot field, right connections with other researchers), you can join the fray that is the academic job market, and scrap for grants to hang onto the job. If it doesn't, it becomes harder and harder to stay a postdoc: fellowships are mostly limited to new PhDs, grants don't have enough room for non-student salaries, and institutional policies force you out.
I'm extremely skeptical that any PhD can "easily" obtain a salary of $300,000 without negotiation. Maybe 5+ years ago a few could, if they were ahead of the AI game. But what hiring manager would you be fooling today?
I'm sure there are a few PhDs here that will prove one of us wrong.
That said, I agree with your sentiment.