Are you from Holland? And how come you think you are taking a risk? Even you continue and complete your MS., you'll risk not getting the job you want later.
Anyways, back to your question. Last year I was in the same position as you do now... am 23 now and holding a bachelor too... am very eager to learn and in upgrading myself, but I believe that studying without any work experience won't take you up to a higer level.
My job hunt during last year was terrible, cause 95% cases were asking for experienced ppl. No matter you were holding a Master/Bachelor degree or simply some certificates or relevant courses, all companies were requiring work experience!!!. I felt so ashamed that right after my study in 2003 I didn't work right away in the field I was into. ...> resulting being neither a recent graduate nor someone with relevant work experience now.
In the meantime I am lucky to have also a job offer in HK starting soon. My choice for this is because I need work experience and challenge to put my knowledge into professional practice. A master degree? maybe in future, but I'm sure that I still need to learn/study besides working.
For you, maybe you can think about this: the job offer you have now... is an opportunity for you to explore and engrave yourself on the work floor. These chances won't be there for you to grasp everyday. If you really can't stand...then you always have the option to get back and continue your Master, but then you have experienced it at least.
And like the ppl say here... having work experience accomplished with a MS. is much worthy than having a MS. and being a starter.