Starting an independent brokerage firm?

Is starting your own brokerage firm as easy as buying a seat on an exchange? Obviously there is computers, software, facilities, membership qualifications, marketing, and skills involved but does owning a seat on a stock exchange essentialy allow one to "make the spread" rather than "pay the spread" and have an overall more direct way of trading?

I am trying to get a better understanding of brokering, day trading, and investment banking.

Relevant and helpful information is appreciated, thank you.