My unusual situation

[Needingadvice]

My dream in life has always to work in the field of IR (NGO/development).  I have a competitive application and was accepted to several top programs last year but received no funding and decided that it was too expensive.  After turning offers from my dream programs, I've been pretty depressed with my life.  The reason it's so hard for me is because I have a really good (unrelated) job with my family.  I don't want to say what it is, but it's a 6 figure paying job with top benefits and loads of vacation time.  Is it nuts for me to leave my current job to study IR?  The money simply doesn't make me happy.

My other question relates to working while studying.  My current job would be VERY flexible with me working one or two days per week while studying and full-time during winter and summer breaks (this would GREATLY reduce future student loan debt).  But since the job isn't really related to IR, how much would it affect my future employability?  Could future related internships fill the void?  Do people in their mid-30s even bother with internships??  My program of choice is SAIS.