It’s money well spent if you view the cost of not doing it as another war that leaves half the world’s industrial capacity in literal ruins as happened several times before.
I’m not saying this is true, but it’s the motivation.
A war that was very good for what the US economic juggernaut has become. We may be significantly better off maintaining great relationships with our Western Hemisphere countries and let the oceans protect us.
I’m not saying this is true, but it’s the motivation.