Defence spending is only as good as the government that controls it, but you can't be serious if you're discounting the importance of military readiness at all times, given the world we live in.
The UK's military spending has always been much more justifiable, especially given that the country actually spends a lot on education and healthcare too (and I will argue that both of them are some of the SOTA systems in the world currently, in spite of their challenges).
But even if you want to do that, why don't you go just a couple more years further and argue that Bosnians should've been left to be genocided?