I think it probably helps (for people like me) that the UK PhD system is rather lighter weight than that in NA - I spent about 3 years and 4 months on mine, which I considered a very acceptable tradeoff for the learning (and ability to work on a project I was really interested in). My lifetime earnings will probably be a little lower, but the flipside is I'm now equipped to take on much more interesting jobs than I was beforehand. If the timescale had been closer to 6 years I would be more inclined to think twice about it.
edit: I don't mean to imply that a PhD is for everyone - I have friends who dropped out who made absolutely the right decision: they didn't want to become academics and had lost interest in their subject. If anyone is in that position they absolutely should drop out. The uninformed supposition that skills gained during a PhD are useless is frustrating to me, though - I really honed skills like the ability (and motivation) to investigate a topic area, present my work clearly, and learned a whole load of new technologies along the way. These have all been invaluable to me - far more so than a little extra time in industry would have been. I was certainly at a disadvantage at 0 years in industry compared to someone else with 3 and a bit. A few years later, though, and I feel at an advantage.
I guess I'm also quite defensive about PhDs because mine holds a special place for me - it was during that time that I discovered how much I love to learn. As a result I'm far more motivated to improve my knowledge than I ever was before.
edit: I don't mean to imply that a PhD is for everyone - I have friends who dropped out who made absolutely the right decision: they didn't want to become academics and had lost interest in their subject. If anyone is in that position they absolutely should drop out. The uninformed supposition that skills gained during a PhD are useless is frustrating to me, though - I really honed skills like the ability (and motivation) to investigate a topic area, present my work clearly, and learned a whole load of new technologies along the way. These have all been invaluable to me - far more so than a little extra time in industry would have been. I was certainly at a disadvantage at 0 years in industry compared to someone else with 3 and a bit. A few years later, though, and I feel at an advantage.
I guess I'm also quite defensive about PhDs because mine holds a special place for me - it was during that time that I discovered how much I love to learn. As a result I'm far more motivated to improve my knowledge than I ever was before.