If you want a PhD for the money, or the glory, or you can’t think of anything better to do, then yes, its a stupid life choice.
If you go into eyes wide open it with a plan, and a goal, and you love the work, and you understand the risks and are willing to take them, then it is stupid not to do it.
I loved grad school (and it didn’t take 7 years - more like 4 and a bit). I did a one year post-doc and got a tenure track position at one of the best places in the country. But I had a plan. And it paid off. I have a great job, and am well-compensated doing what I love.
But it was a risk. I wasn’t willing to post-doc forever. If I hadn’t gotten a job within 5 years, I would have dropped it and gone into industry or government.
Most people in grad school are worried about whether their next experiment will work. If they are very far-thinking, they are worried about writing that next chapter.
I was thinking about my future faculty position as a third-year grad student. I had my first NIH grant outlined and half-written before I graduated (even though I wouldn’t be able to submit it for another 3 years). I wasn’t thinking specifically about finishing that next chapter, but rather what it would take succeed as a faculty member. I rightly figured that if I did that, the dissertation etc… would take care of itself.
You need to be lucky to succeed in academia. You can be the best in the world, but without that break, you won’t succeed. But its not all luck. Even now, of my students and post-docs I can pick out the ones who I think have a pretty good shot. Its not that they are smart (everyone is). Its not that they work hard (they all do). Rather, they PLAN. They have original ideas, and implement them. They are ambitious, but also focused about it.
And contrary to what is says above, the best advisers don’t hold onto good people forever. Its part of my job to move people along, especially the people whom it would benefit me most to hold onto.