As others have said, it's a personal judgment call. I wasted my 20's that way, and have no regrets. The PhD did not help my career one iota. But the journey was worth it, and I accept the price I paid (which is entering the job market a little older, and thus retiring a little older).

If someone wants to keep that up with postdocs, more power to them. I just observe that there are a lot more postdocs who regret their journey than those who stopped at PhD.