Depends on two things:
1) One's priorities. Some might view the aggregate (the country) as bigger thing than individual people. Under this view, the importance of the lives (or worse, the importance of having comfortable lives) for a present generation can be deemed worth it to the freedom, prosperity, etc. of generations to come (and to the continuance of the country itself and its state and way of life etc., which in some cases might be totally obliterated by decline, e.g. Rome).
2) The question presupposes that avoiding war would avoid "brutal violence, intense prolonged suffering, anguish and grief" later. In many cases, that's not the case. Instead, the decline can bring with it violence, intense prolonged suffering, anguish and grief -- only without anybody doing anything before to resist those things.