It's never too late. Takes one "decision" to change, one effort to pick something you want to do and then work on doing it! Yes the past may be "wasted" but that has nothing to do with now/any future.

I'm 56. I didn't get married until I was 39. I did work in my youth but at "simple" jobs beneath my education, etc. Not many friends, lots of therapy, etc.

Have you tried writing for publication? There are ways of making money that don't require one "go out" and get a job. Do you invest any of your inheritance at all so it won't poop out on you as fast?

What do you want? You can't have your youth back, that's correct but you can laboriously work to change your habits (of thought and action) if you want to. I barely graduated from college in 1972. Now I have a 4.0 on my second degree. I didn't figure out that "problem" until 1991 when I was taking a class and realized I was taking it for me, not the public, my stepmother, the professor or anyone else. I got truly sad taking the final exam that I hadn't studied a bit harder and the lightbulb went on with that sadness/regret. But I didn't change overnight and start doing my homework, doing the reading for classes, etc. It's been an uphill struggle for the last 15 years. The problems change too, as I go along. I'll get an A in this course, whether I read the texts or not but I want to do the work, read the texts for me and who I want to be. That's one thing I started a couple years ago, I use "I want" and underline it when I do use it in my journal.

What do you want? If you would enjoy the PhD program, go for it! If you want the job, work on that (and it won't be your last chance; if you don't get it think of it as a preliminary trial at interviewing, analyze what went wrong and work to "fix" that). Regretting doesn't do anything for you now. Find something that might make you happier now/in the future and work on that.