And building a lot is very expensive. The US - which is choking on the inflation and debt caused by trying to finance everyting including its MIC, Britain which is holding on to its nuclear deterrent by a thread, North Korea which has beggared its population - nothing new for them however - France which is holding its own, Russia - which a military industrial state, and China which has had an enormous economy to draw on as well as stealing US secrets and personnel trained in the US.
It's not as easy as it looks and it doesn't even look easy.
You seem to be trying to give the impression that the U.S. nuclear arsenal is not the best in the world, with the best delivery systems.