@OP, Invest or creating exchange site is a good idea but required alot of research with experienced/expert in block chain and internet security not an organization that provided a source code and later be the same group to hack the site.
I will advise you to read the basic step provided on here but i dont recommend their service cause i only want you to know all what you need.

There is much already existing crypto exchange site but that doesn't mean there's no room for another one since crypto business is a broad industry and whats important the most is offering people some unique features which was one of the reason people seem to acknowledge Binance cause no exchange site should be totally and that include Binance.