>>720614419
Because naval transport was *the* method for large-scale trade up until ~200 years ago, before trains or larger-scale land transport. If you didn't have a coast or a river, you could only trade in small quantities, and couldn't enjoy the benefits of the economies of scale. The bigger your economy as a result, the more you can flex militarily and the more you have to protect, ergo the bigger the navy and the bigger military presence.