There has been lots of talk on the intertubes about this topic. Much of it has been from folks near the decision points. At my end of the age spectrum, I'm seeing it a bit differently. My perception isn't more right or wrong. It's just different.
So to start, it is import to remember there are choices being made here. As my father used to say to me: no one's holding a gun to your head and saying "be a postdoc or I'll blow your brains out" (or something like that, his exact words fade with time). But, as a good economist would say, The more information you have, the better decision you can make. Be informed about the future. Real numbers about who makes it and who doesn't. PI's let your trainees see what is involved in making sausage. Trainees, get beyond your views (good and bad) about what PI's actually do. And get beyond both your imposter syndrome and your special snowflake syndrome. Neither serves you well as this point.
Arguing that it's not fair to work that hard and not get paid like people industry is fatuous. That's like arguing that gravity isn't fair as you fall out of the tree. The world is. There are parameters, and guidelines and rules and a couple of laws. Anyone making a decision about what to do with their postdoc is (relative to the rest of the world) in a fairly privileged position.
I'm not saying it's an easy choice. Or in fact one that everyone can make in their own best interest... Family, commitment, children, all of these compromise that decision. Let alone fair. Somebody will have more money, brains or good looks and be making a different decision or have the option of a different decision. Being a scientist is bloody hard work. Hard. Work. I'm not saying you don't work hard. I am sure you do. But its hard work in a Red Queen Context.
My concern here and now is that we (the people picking postdocs) are selecting for wealthy individuals who can "afford" to do this, and keep their lifestyle. We who have some control over the "fairness" may be, could be, aiding and abetting an unfair situation. When all the FLSA stuff was happening and people were looking at raising postdoc salaries, I heard junior colleagues agonizing. If I raise the salary of this NSF postdoc, I will have to cut my experiments. (Remember that NSF grants are an order of magnitude smaller than NIH). Those junior faculty are just trying to survive, too. What angered me, too, were the senior colleagues with five postdocs who decided to let one go to cover the raises of the others. That's a hard decision, keep five at a lesser wage, or drop one, and raise four up? The answer, to those of us who believe that the problem may be too many mouths at the trough, is that you don't hire five postdocs in the first place.
So young padawan, here is the world. You can make a lot more money doing something else. I know lots of people who did. Or you can make less money doing science. It's a hard road. There are no guarantees for those walking it.
Note after writing: Ola had a comment on the managing people post that says similar things, in a different way. It's worth adding here:
As others have said, as a junior prof you need your ass at the bench and then every other waking hour is writing grants. If you're not submitting 5-6 grants a year for the first few years, you're not doing it right. Yes it sucks! You have to teach, run a lab, manage people, do department politics crap, mentor people, manage money, write papers, and have a life outside the lab possibly including young children. In short, you have to be all of the things to all of the people. This is not new, this is part of the job and has been for as long as anyone can remember.