Yes continuing on into postdoc is another 3+ years of opportunity cost, certainly it does add up quickly. But OP was implying that PhD students actually had to pay for their degrees which is not true. Most people will finish PhD before they are 30, if you compare to top SWE or finance jobs then sure there is expensive opportunity cost, but compared to entry level jobs more generally it really is not a huge deal. Most people doing a traditional STEM PhD wouldn't even be able to get one of the "high roller" jobs out of undergrad, because only a handful of majors are considered for the most part. A pure neuro undergrad wouldn't learn enough CS in school to be considered for a FAANG.
IMO postdoc is where people really start to get set back - you don't get benefits like free health insurance or subsidized housing anymore, you are getting older with additional life expenses, and you aren't getting a degree that can open doors to additional jobs anymore. You are basically just continuing to chase a university career at shit pay by the point you reach a postdoc. The worst part is that people are forced into postdocs almost immediately, because you literally can't get one after you are a certain number of years past graduation.
I don't disagree that as a society there are better ways. But as an individual actor unless you make an absolute killing with some start up or something there is no way you can afford to do proper biology research (for example). Perhaps if you're willing to move into some specific niche based on feasibility, but you'd have very little freedom in what questions you could ask this way. Beyond money there are also logistical questions surrounding care of animals or possible clinical collaboration, so unless you're happy doing in vitro work only this is another can of worms for someone attempting to be an independent researcher.
IMO postdoc is where people really start to get set back - you don't get benefits like free health insurance or subsidized housing anymore, you are getting older with additional life expenses, and you aren't getting a degree that can open doors to additional jobs anymore. You are basically just continuing to chase a university career at shit pay by the point you reach a postdoc. The worst part is that people are forced into postdocs almost immediately, because you literally can't get one after you are a certain number of years past graduation.
I don't disagree that as a society there are better ways. But as an individual actor unless you make an absolute killing with some start up or something there is no way you can afford to do proper biology research (for example). Perhaps if you're willing to move into some specific niche based on feasibility, but you'd have very little freedom in what questions you could ask this way. Beyond money there are also logistical questions surrounding care of animals or possible clinical collaboration, so unless you're happy doing in vitro work only this is another can of worms for someone attempting to be an independent researcher.