As a PhD student, I'll lightly disagree and say that I'm happy in my PhD. I like doing research every day and having freedom to work when and where I want, on what I want. It's much better than the year I worked as a software developer working on things I found boring and repetitive. I would definitely say I've had fun. Of course, it's not always fun, and I know I've been lucky as far as advisor and project randomness. But the harshness of the link you posted seems unnecessarily severe.