None of that has anything to do with why starcraft is popular, though. Starcraft has a long history of organized professional competition, and that's responsible for sustaining interest in the game.

At first people played Starcraft for the campaign, internet access in late 90s wasn't common enough for a game to thrive on mostly online multiplayer. And it was popular back then. And playing on LAN was more of "20 mins no rush" thing.

So: money, gambling, ego bloating, greed, eye candy, narcotics?