well I for one thank the mathematicians engaging in number theory when there weren't any practical applications. it took a few hundred years for the technology to catch up to where its the reason we can even have a semblance of privacy in the modern age via cryptography.
the lesson there is that we have no way to know what the the abstract useless math today will enable us in the future.
the lesson there is that we have no way to know what the the abstract useless math today will enable us in the future.