And somehow a fence/net/security will stop them? They are US trained military personnel. They are trained to overcome fences and nets and security! The only means of deterring them is an intervention.
My psych. class dealt with suicide and the various "types" of suicidal people.
-You have the ones that are out for attention, they don't actually do it, they just crave the attention it gets them.
-You have the straight up suicidal people who do it because they are in a funk and they feel like there is no way out and living isn't a compelling option.
-You have the show offs who, for some twisted reason, feel that by killing themselves in a grand way they will be heroes/remembered/ect..
-And finally you have the "trying to escape..." type of suicidal people. They do it because they honestly feel that they are being chased or something and that death is better than what will happen if they are caught. These types shouldn't be confused with the second kind, as the second kind does it out of depression and these guys do it out of delusion.
I'd assume that most military types probably fall into the 2nd or 4th group (leaning more to 4th).
Of those groups the only ones who'd be deterred by a fence/net/security would be the ones who are just in it for attention and the show offs. The show offs want to be one of those 1000+ who have killed themselves on the Golden Gate (or anywhere famous) and if they cannot get it there then they will probably walk away. They may try it elsewhere but often times once they are met with a wall they stop.
The attention getters will be deterred, but who cares, they don't really pose a threat to themselves, unless they slip by accident.
The other two groups, and these two make up the VAST majority of suicidal people, will not be deterred by anything short of a intervention.
So it doesn't really seem like a deterrent is going to be very effective. Using statistics and averages I'd say that of those 1000+ who killed themselves off the Golden Gate, only maybe 10 were the show offs (the % who are show offs is so minuscule, something like 1%)