"No one has yet discovered any warlike purpose to be served by the theory of numbers or relativity, and it seems unlikely that anyone will do so for many years."

Yet here we are a few decades later with the fundamentals of modern cryptography based on number theory results. Specifically, the difficult in factorizing the product of two primes into the original prime factors (RSA).

So while this specific might seem abstract and without purpose, it often goes in mathematics that we'll find the purpose for it later.