This hits close home for me. (Well, giant sea monsters not included)
I've had a few similar conversations with one of my grand parents and a few other people, before and after I entered and completed my conscription service. Grandma had the same arguments, that she lost a few family members because of Winter War and Continuation War, and sees no point in wars. Therefore, I shouldn't take any part on the matter. Some accuintances also argumented, that what's the point of armed forces during peace? Why not be friendly instead and get rid of all the guns in the world?
I did agree that wars are indeed pointless, senseless stuff. Waste of lives. And every effort should be done to prevent one from ever happening in the first place.
But, in my opinion. It does no good to stuff one's head into bush if the opposing force decides to march over the border without a visa and good intentions, and with guns and bombers... And it matters not being pro-peace, when the opponent isn't. Wise man once said, that "every country has an army. Their own, or someone else's." In the latter's case, the question is: Were they invited, or did they invite themselves?
If they don't care about your country's sovereignty, chances are high that they won't pay any mind to your infrastructure and well-being either. One of the ways to prevent a possible war is to prepare for one.