Apart from the risk of violent death or life changing injury while they are serving, there's also the increase in domestic violence, suggesting it does a number on mental health:
From: www.kcl.ac.uk/news/more-than-1-in-10-armed-forces-personnel-have-experienced-intimate-partner-violence-and-abuse
New research from the King’s Centre for Military Health Research (KCMHR) at King’s College London has found that Armed Forces personnel are significantly more likely to both experience and perpetrate intimate partner violence and abuse (IPVA) than the wider civilian population.
The research, published today in Lancet Regional Health – Europe, is the first of its kind looking into IPVA in UK Armed Forces personnel, and found that both men and women with military experience were over three times more likely to report IPVA perpetration and almost three times more likely to report IPVA experience than those in the civilian population. The researchers say this reinforces the need for a specialised Domestic Abuse Strategy that takes into account the military specific drivers of IPVA.
The outcomes also aren't good once they leave:
From www.stoll.org.uk/nhv-news-post/homelessness-is-rising-at-a-startling-rate-but-solutions-are-available/
There is a variety of reasons why former soldiers and other military personnel can be vulnerable to homelessness. Some find that a,fter leaving the structure and focus of military life, where many day-to-day duties are taken care of, they are not well equipped for the complete autonomy of Civvy Street. As veteran Alan Marshall, who served in the Army for eight years, puts it:
During my time in the Armed Forces I didn’t learn many of the skills that are inherent to civilian life – things like managing a tenancy and organising rent and council tax payments. It was actually a massive shock when I left the Army to have all of these responsibilities that I wasn’t prepared for.
Combine this abrupt change in lifestyle with other potential issues faced by veterans – including finding work, relationship breakdowns and health issues such as addiction or PTSD – and it’s not hard to see why some ex-soldiers have difficulty maintaining a secure and stable home.
I had a grandfather in the navy and an uncle and cousin on the other side in the army, and would not advise it. All of them quite damaged by the experience.