It's a dead end, in most cases.
Most FLGSs make the majority of their money on sales of Magic cards. Everything else is secondary. It's not because the owners want it to be that way - it's just the only thing that sells well enough these days in a brick-and-mortar game store setting to give them any chance of making rent and paying their bills.
In order to remain competitive, you'll have to provide space for people to play in the store AND put time and money into running tournaments, knowing full well that 99% of the people who use those things are not going to buy anything while they're in the store.
Most of the RPG books you buy and put on the shelf will sit there for a LONG time, eating up a lot of valuable shelf space until they finally sell (if they ever do).
You will be competing with both the Internet and Barnes & Noble when it comes to RPGs, and with Wal-Mart when it comes to selling Magic cards. That's almost impossible to do when it comes to price, so you'll have to have some very strong incentive(s) of some sort to lure people into the store.
You will have a very hard time paying employees, especially if you go above minimum wage. That will cause a high turnover and will not give you great employees, for the most part, particularly when it comes to customer service skills. You will have to work extremely long hours every day, probably seven days a week, to even make a decent stab at it. Remember, the store needs to be open when the customers want to shop, not when you want to work, so you'll have very little time for a social life, sick days, closed days, vacations, etc.
There is a game store owner discussion board on Delphi Forums that delves pretty deeply into the financial realities of this sort of thing.
You should never quit your day job and start a business until you have tested the waters first. Consider going to work in a game store on the weekends for a year first to see what you would really be getting yourself into.
If you are talking about getting into the business of making games, that's a different beast altogether. Very, very, very few game designers make a full-time living at it.
