I'm sure the number one thing bit coin is used for is trading but that wasn't its original use.
Well, this kind of thoughts only knew Bitcoin as an investment tool and a get rich quick mentality. You could actually google it and type what is Bitcoin, I'm pretty sure google will definitely give you enough answers why Bitcoin was created by Satoshi.
I guess everyone who wants to learn about Bitcoin knew why Bitcoin was created.
Lemme tell you, the number one thing Bitcoin is used for in simple words. To eliminate the need of central authority when financially transacting from one person to another globally.
Or you're always welcome to read Satoshi's whitepaper posted above by BlackHatCoiner.
I thought BTC was going to replace
You thought wrong. Bitcoin was not created to replace X or Y. It was created to fill a gap in our world for a medium of exchange that is not and can not be controlled by any centralized authority.
Definitely!
This is what people keeps forgetting about when they say Bitcoin will soon replace fiat or soon replace the traditional banking system. Satoshi for sure didn't write something like Bitcoin replacing something in the whitepaper.