[dalke]

My PhD program is 'on hold' as well. It's been 15 years, but someday I plan to get back to it.

Depending on who I talk to, I say "I found I liked programming better than my research", "I grew distrustful that the simulation methods were meaningful", "I wasn't getting the support I needed from my adviser; I was one of 14 students and he traveled a lot", and "I was doing too much CS for a physics degree, and too much physics for a CS degree. Only in retrospect years later did I realize that I was actually interested in molecular informatics." (I've spent the last 20 years working in structural informatics, bioinformatics, and chemical informatics.)

I don't think you understand the difference between undergraduate and graduate schools. Grad school is more like a job. You don't "drop out" of working for McDonald's, you quit, and explore other interests.

Also, it's not like leaving graduate school is uncommon. Attrition rates in graduate school (math and physical science) are 25% within the first four years. See http://www.insidehighered.com/news/2007/12/07/doctoral#sthas... , and after 10 years of graduate school only 57% end up with a degree.

See also http://chronicle.com/article/PhD-Attrition-How-Much-Is/14004... , "She rejects the term "dropout" to describe someone who leaves graduate school. I agree with her that the word "connotes individual failure" when someone may simply be departing for a better opportunity."