I am wondering how this works...I see people say they make a good living doing this but you must need a good amount of coin to make this work.
Anyone that does this give me some insight into how this works?

you have to keep a couple of things in mind:
1) if other people are making money or huge amounts of money by trading bitcoin/usd it doesn't mean you can do start doing this without any prior experience.
2) do some research about exchangers that you want to put your money in. use google search and also search in the forum for their announcement threads and problems that people ran into with those exchangers.
p.s. i personally like trading altcoins since i am better at it rather than trading bitcoin, besides i was able to make more from trading alts.