I'd say there is a lot of "sport" behind it.
considering that sports that are considered sports don't necessarily mean that you have to "run around", I for one would not then consider golf as a sport but it does otherwise.
sure there are physical elements to golf, you are certainly a better golf player if you are in shape and in more control over your body, but the same can be said for elite gameing too, you need to stay in shape in order to be more alert, hightened ability to concentrate, body response, and so on and so forth.
and golf is just an example there are several more sports that don't require much movement.
btw, there are high leagues in more games other than Starcraft and FPS games, Arena RPGs like HoN, DotA and LoL have grown pretty big, fighting games like Street Fighter have a huge ammount of money circulating in tournaments, another RTS that's somewhat big within E-sporting is Warcraft III, I'm no expert but these are games I know have pretty nice clans and tournaments.
btw, sports channels in sweden do occasionally show Counter Strike tournaments and games, and a few sport bars in stockholm are known to have the occasional e-sport evenings, sure not as badass as korea but we are on our way there =P