I first came across YMOYL in the late 90s. It was a bleak period for me. I'd moved halfway across the country for a job which didn't work out (through no fault of mine). My prospects of finding employment in my field of choice, for which I'd spent years training in grad school, were grim. I was about the start a job for which I was overqualified in a place where I knew no one.
In short, I felt my life had completely spun out of control. I think that was the main source of the book's appeal--that there was something I could do to make myself feel like I had control over some aspect of my life, at least.