Hi,
the attrition rate in a PhD program is extremely high even for a full time student. Even the brightest students still face difficulty to get ahead in the publishing game. A lot of people expect going to graduate school with the good intention to nourish their mind, enlightenment, etc.., which is all well and good, but the truth is in a PhD level, you are expected to be a producer of knowledge as opposed to being a consumer of knowledge. I wish someone would have told me earlier in my graduate school day that this PhD program is more of a work than it is a leisurely activities that you do for fun/enlightenment.