'Keeping Americans safe' is not on their agenda. If it were, they wouldn't be sticking America's hand into Middle Eastern quagmires, like the one that radicalized OBL and provided a training ground for his friends and allies. If it were, they wouldn't be working half as hard in demonstrating to hundreds of millions of people that yes, America does, in fact, mean them harm, and is happy to inflict that harm on them.
Not really.
When you look back, seeing how things turned out, history looks different than it almost certainly felt to most people at the time.
It took 250-300 years for the Roman Empire to collapse. You could make a pretty strong argument that the US has been in decline for decades, and that cracks in Pax Americana were already forming during the Vietnam War era.