You're being downvoted because the question looks like snark even if that isn't what you intended.
Other people have answered the direct superficial question: A lot of this stuff is used already to make stuff work. TLS (for HTTPS) has been mentioned, but if you have a work laptop it's probably using Full Disk Encryption, if you use git for revision control the content addressability that makes that possible is only safe with cryptographic hash functions, the reason a bored teenager can't listen in to all your mobile telephone calls is cryptography, the reason it's very hard (and ought to be impossible if they'd done a better job) to use a chip-and-PIN credit card without the PIN is cryptography and so on.
Now the more subtle question: Do you need any of this? Well no for a lot of jobs you don't, just as a car mechanic doesn't need a grasp of aerodynamics to do their job, but if they fancy designing jet aeroplanes that's going to be a problem. This course is about applying cryptography but it isn't an engineering bootstrap course, so it expects you to understand why rather than only learning how.
Other people have answered the direct superficial question: A lot of this stuff is used already to make stuff work. TLS (for HTTPS) has been mentioned, but if you have a work laptop it's probably using Full Disk Encryption, if you use git for revision control the content addressability that makes that possible is only safe with cryptographic hash functions, the reason a bored teenager can't listen in to all your mobile telephone calls is cryptography, the reason it's very hard (and ought to be impossible if they'd done a better job) to use a chip-and-PIN credit card without the PIN is cryptography and so on.
Now the more subtle question: Do you need any of this? Well no for a lot of jobs you don't, just as a car mechanic doesn't need a grasp of aerodynamics to do their job, but if they fancy designing jet aeroplanes that's going to be a problem. This course is about applying cryptography but it isn't an engineering bootstrap course, so it expects you to understand why rather than only learning how.