Because I have knowledge/training of/in Anti-submarine warfare, surface warfare, mine warfare, and air warfare projected by naval forces. I also have historical and technical knowledge on the subjects.
In addition to those knowledge sets I have insight into the capabilities of other country’s navies and the regions upon which they can project those capabilities.
So explain to me if we have more aircraft carriers than the rest of the world’s navies combined, more guided missile destroyers than the rest of the world’s navies combined, more nuclear submarines than the rest of the world’s navies combined, more amphibious helicopter ships, more landing ships, more auxiliary ships, more of just about anything else you can name, and taking into consideration that most of the rest of the world’s navies are on our side, then why do we need 350 ships? Are we expecting all the other navies except China and Russia to go out of business?