Its very much a personal decision, but I think weighing it up: 3 years and then freedom has to be a better choice than 9 years without freedom (and the risk of being shot down in Afghanistan or something). I also think you could probably get some reasonable careers advice from somebody at your nearest University. They’re usually willing to discuss your options and advise you if they can. Is there any chance that you may be able to pursue these subjects vocationally through a scientific organisation or a charity, or something similar (ie not the military)? Anyhow, some ideas for you. Hope you take your time and seriously weigh up the pros and cons. Good luck!