If the article at the top of the thread is atypical of a tenured professor,
this post is absolutely typical. I've heard this speech a million times. If you ever need to hear it again, ask any professor to give it to you and they'll happily oblige.
Undoubtedly, most tenured professors are having an "absolute blast". Why shouldn't they be? They are the end product of a rigorous system of selection for their particular set of personality traits. If you're not the kind of person who adores being a researcher to the exclusion of all other thoughts -- if you are not either a truly diehard optimist, or the most stubborn person you'll ever know -- you won't make it to where this guy is.
The career advice here is good, solid advice, as far as it goes. But the parody of this would be fun to write, and might contain equal amounts of truth. ("(2) Iterate until you find a group that looks excellent, or until you discover that all the excellent groups have a waiting list, at which point you need to either quit grad school, apply for a personal fellowship and win it, or work for whoever has the grant money to pay you.")
No time for extensive parody today, though -- besides, the guy at Piled Higher and Deeper has covered that ground better than I ever could -- so I'll leave you with this caveat: Very, very few of the people you interview with in a research group will ever tell you that your academic career is a waste of time and that you should just leave, even if it's true. They've got a very strong incentive to recruit you, so that you can apply your inexpensive intelligence and energy to their projects. They've got an incentive to be careful what they say to you, because if word gets back to their colleagues that they are discouraging prospective students it might derail their careers. They also have an even bigger incentive to keep fooling themselves.
And, you know, academic scientists really don't like pain. They're not drill sergeants. Taking starry-eyed optimists, most of whom remind you of yourself, and kicking them in the chest is not a lot of fun. It's for their own good, but it feels like euthanizing puppies. It's just so much easier to encourage them to follow the same path that you did, and to let time and nature and bureaucracy take care of teaching them the harsh realities of life.