> * age 30-35: working as a post-doc for $30,000 to $35,000 per year
You can earn more than that (and younger) if you're prepared to travel outside the US, though it's still not great. I'm hesitant to share personal details, but I'm personally in my mid-twenties and just starting a "postdoc" (in a sense; still waiting to defend my thesis), and I'm earning quite a bit more than that, albeit in an expensive city and with a large tax/student loan burden.
I'd like to do a postdoc in the US next year, but I'd have to take a large pay cut to do it, which is something I'm on the fence about–I figure you're only young once, and money isn't everything, but I can't help but feel I'd be being taken advantage of just because I happen to enjoy doing science, and the additional opportunity cost would be high too. Is it worth it? I'm not sure.
Beyond that... I wrote a much longer comment but deleted it. The fact is, academia is in an unhealthy place right now, and there's quite so much wrong with it that it's very difficult to articulate. Where do you begin? Whether to even stay in academia or leave is a question that seems to be discussed a lot lately, certainly among my colleagues, and I expect to see a lot more threads like this in the future.
Edit: Actually, I should add, that despite being in a decent place now, I had to unexpectedly work without pay for a time last year due a (ahem) 'funding hiccup.' This experience was so very terrible at the time that I'm surprised I didn't just give up on the PhD right then. To explain: in the UK, STEM funding is typically 3 years, and when that runs out you're in trouble: you can't go and get another job because you need to finish your thesis to get your PhD. Most people can't finish a PhD in 3 years (unsurprisingly). Some people manage to get extra funding from somewhere or start postdocs while still technically writing-up, but most people don't. Some people are told there will be extra funding which never materialises, or doesn't arrive on time. Several of my friends ended up going back home to live with their parents to write-up (and are still there); this is not uncommon. I know someone else who ended up living in a hostel. Once you've started the PhD you're invested, and the longer you do it the harder it is to walk away. The real kicker to me is that a lot of people accept this and think it's okay.