^ actually, Isaac Newton, the greeks, the Chinese, and soem other guys all helped make it.
Isaac newton is the person who formalised it, and some other dude proved it where Isaac failed.
I can assure you it is not useless.
Furthermore, I have another year of HSC maths to go, another 4 years of undergrad uni maths, and probably another 4 or 5 years of graduate uni maths, like Ph.D and stuff. That's about 10 years of maths left to go, excluding the fact that my job will probably end up being maths stuff.
I can safely say my mathematics life has just begun.