Full disclosure: I haven't read the book myself. Logically, however, expressing regrets does not say anything about whether a specific course of action is better. By definition, one can only regret living one's life in a certain way if one actually did - so perhaps a high incidence of people regretting "working too hard" is simply indicative of working a lot being the most common experience, rather than any special reason why a life spent working should be regrettable.

And back to Gregg - he's personally been an inspiration to me. Who would I be to question his life choices, but I for one am grateful for the path he did choose to take.