One can find the application to this quote pretty much everywhere, everywhen, even in small personal situations, so once it spread it stuck and outlived the Rome itself because it does correspond to what we sometimes think and do. In soviet times (another dead empire) there were a couple of the same-meaning proverbs, like 'alarmed, thus got armed (in time)' I used when I prepared for things like exams, job interviews, long camping trips and stuff, and I'm pretty sure your culture has them too.

I believe that Einstein was very optimistic and said that too early, or dreamed of the future when wars over beliefs, ego or profits aren't a usual occurence. But we as humanity haven't arrived there yet. One of the ways this can occur is if we would see the war not worth it for a long time, to get used to it, and Europe mostly got this by now within itself, but not against external threats. As, so it happens, there are still rogue actors who can start their shitty crusade on their border. And if we won't be so europocentric, the Middle East and Africa and Asia has a lot of war axes dug out for their peers, there are hot and cold conflicts going on even if they aren't covered in what news sources we can read.

Star Trek: TNG's first season has a little mention of how we humans came here, through unimaginable wars and atrocities, before we aknowledged that our ways are wrong. I hope, we would be better and won't see WW3 (or WW4 with sticks and stones as Albert said) play out before we reach something akin to their fantastic future. We may need to come to the parity and agree to tone it all down, and have a century of peace, before we even get into the mentality characters have in this show.